Bearcorn: A Mysterious Parasite from Eastern North America

Bearcorn (Conopholis americana) is one of those plants that really challenges mainstream assumptions of what a plant should look like. It produces no leaves, no chlorophyll, and all you ever see of it are its strange reproductive structures. One can easily be forgiven for thinking they had encountered some type of fungus.

Bearcorn is an obligate parasite on oak trees. It simply can’t exist without access to oak roots. From what I have been able to gather, the preferred hosts of bearcorn are the red oaks (section Lobatae). That is not to say the exceptions have not been documented. At least one author claims to have found bearcorn attached to the roots of a white oak (Quercus alba) and even earlier work suggests that American chestnut (Castanea dentata) may have served as an occasional host as well. Regardless, if you want to find bearcorn in the woods, you would do well to search out red oaks first.

According to those who have run germination trials, bearcorn seeds must be in close proximity to oak roots in order to germinate. Some sources say that direct contact is needed whereas others claim that seeds have to be close enough to detect root presence. It is likely that some sort of chemical cue is what initiates the process and this makes sense. For a plant that relies completely on another plant for its water and nutritional needs, it doesn’t make much sense for bearcorn seeds to germinate anywhere but near oak roots.

Upon germinating, the tiny seedling needs to act fast before its meager energy reserves are exhausted. If lucky, the growing seedling will come into contact with an oak root and begin developing a strange organ referred to as the nodule or tubercle. Thus begins its parasitic lifestyle. The tubercle continues to grow throughout the life of the plant, developing into an amorphous, woody blob that continues to envelope more and more oak roots. Its within the tubercle that all of the parasitism takes place.

Cells within the bearcorn tubercle penetrate into the vascular tissues of the oak root, stealing all the water and nutrients the plant will ever need. Over time, the bearcorn tubercle coaxes the roots of the oak to fan outward like the crown of a tiny tree. In doing so, bearcorn is effectively increasing the amount of surface area available to make more parasitic connections. Apparently this all comes at great cost to the oak roots. Over time, oak root size within the tubercle greatly diminishes until some completely perish. Considering the size of some bearcorn populations, one could expect the oak host to fight back.

Indeed, it would appear that oaks are not helpless against bearcorn infestations. Examination of the cells within bearcorn tubercles revealed that as the parasite grows, the oak will begin flooding the infected cells with tannin-rich compounds. Apparently this serves to slow the flow of water and nutrients into the tubercle. There is even evidence that some of those tannins are transferred into the bearcorn tubercle, leading some to suggest that the oak is literally poisoning its bearcorn parasites, albeit slowly.

There is a strong possibility that such oak defenses lend to the relatively short lifespan of bearcorn plants. In at least one study I read, no bearcorn individuals over 13 years of age were found and the average age is estimate to be about 10 years. Perhaps just over a decade is about all a bearcorn can hope for once the its oak host begins to fight back. Good thing bearcorn populations can be surprisingly fecund.

Bearcorn plants reach reproductive maturity at after about 3 years of growth. They flower in the spring and that is when they are at their most obvious. Numerous thick, finger-like stems emerge from the ground covered in whirls of cream-colored, tubular flowers. Though a dense population of flowering bearcorn may look like a bonanza for pollinators, they don’t seem to attract a lot of attention. From what I was able to find, bumblebees are pretty much the only insects to visit the flowers, and even then, visitation rates are low. Apparently bearcorn flowers do not produce any detectable scent nor are they full of nectar. I guess the only real reward is a meager helping of pollen.

Photo by Joshua Mayer licensed under CC BY-SA 2.0

No matter, bearcorn has a nice reproductive trick to ensure plenty of seeds are produced each year - it selfs. The anatomy of the flowers is such that, at maturity, the anthers are in direct contact with the stigma. Even if nothing visits a bloom, it will still go on to clone itself year after year. Once fertilized, each flower gives way to a large fruit chock full of seed. This is where the corn part of the name bearcorn comes from. A stem thick with fruits does resemble a strange, albeit juicy ear of corn sitting on the forest floor. The bear part of the name likely has to do with the fact that bear readily consume bearcorn fruits, stem and all. Working in the southern Appalachian Mountains, I can’t tell you how many times I came across bear scat absolutely loaded with bearcorn fruits and seeds. It’s not just bear either, deer are also very interested in bearcorn fruits.

Lucky for bearcorn, its seeds pass through the guts of these animals unharmed. Hopefully, with a bit of luck, at least one of these animals will make a deposit in an oak-rich region of the forest. With even more luck, some of those seeds might even find themselves nestled in near an oak root to begin the process anew.

Further Reading: [1] [2] [3]

When the Going Gets Tough, Desert Mistletoes Cooperate

Sure, parasites can be a drain on their host, but for those parasites whose entire life depends on a living host, it doesn’t pay to kill. Such is the case for the desert mistletoe (Phoradendron californicum). These plants simply can’t live without the water and nutrients they receive from their host trees. But what happens when more than one mistletoe infects a single tree? One would think that supporting multiple mistletoes would be a dangerous drain on the host tree. However, recent research based in the Sonoran Desert suggests that desert mistletoe has a trick up its stems that involves a bit of communication with its neighbors.

Desert mistletoe isn’t completely reliant on its host for all of its nutritional needs. Though lacking leaves, the desert mistletoe is fully capable of photosynthesis via its tangled mass of green stems. Most of what desert mistletoes extract from their host consists of water and other nutrients they can’t acquire themselves. However, desert mistletoes rarely operate alone. Thanks to their nutritious berries and the territorial habits of the birds that disperse them, multiple mistletoe individuals often wind up parasitizing the same tree.

Heavy infestations may sound like a death sentence for the host tree, especially in the harsh Sonoran climate. However, by manipulating the mistletoe loads on various trees and observing how mistletoes and their hosts respond, researchers have discovered that mistletoes can apparently sense their neighbors and alter their behavior accordingly.

During dry periods, trees become stressed for both water and nutrients. For mistletoes growing on a stressed tree, it doesn’t make much sense from an evolutionary standpoint to increase their demand on the host during these times. Instead, mistletoes growing on stressed trees actually increased the amount of photosynthesis they perform without increasing the amount of water they extract from their host. By altering their metabolism in this way, the mistletoes do not add any extra burden to their already stressed host tree but nonetheless maintain their own fitness.

Amazingly, the situation got even more interesting when researchers experimentally removed some mistletoes. Somehow, depending on their position on their host tree, some remaining mistletoes can sense that their competitors had been removed. When this happens, they don’t go into overdrive and start exacting a greater share of resources from their host. Instead, the remaining mistletoe appear to sense that they no longer have to compete as much and adjust their water and nutrient uptake in such a way that actually allows their host to benefit as well.

Certainly these findings generate more questions than they answer. First, how do mistletoes sense their neighbors? Given their direct links with the host vascular tissues, they could be sensing signals from other parasites that way. There is also the potential for airborne signal detection as well. Also, do mistletoes behave differently when growing near related individuals versus strangers? What researchers have ultimately uncovered is a fascinating coevolutionary system in desperate need of more attention.

Further Reading: [1]

When is a mushroom not a mushroom? When it is a Maltese mushroom, of course!

Photo by Hans Hillewaert licensed under CC BY-ND 2.0.

Meet Cynomorium coccineum aka the Maltese mushroom. Despite the common name and overall appearance, this is not a fungus. It is indeed a plant. Cynomorium coccineum is a holoparasite. It produces no chlorophyl of its own and relies solely on a host plant for all of its water and nutrient needs. It is said to parasitize the roots of halophytes or salt-loving plants and thus, is most commonly found growing in salt marshes in addition to dry, sandy habitats in coastal areas.

Native to the Mediterranian region and extending into parts of Afghanistan, Saudi Arabia, Iran, and Central Asia, this species is really only ever found during the rainy season. Most of its life is spent underground, emerging only to display its flowers. Only when enough energy has been garnished from the host will this plant throw up these strange flower spikes. As you can tell from the picture, the spikes are jam packed with highly reduced flowers. The flowers give off a scent that has been likened to cabbage. It is thought that flies take up the bulk of the pollination of these blooms.

Photo by Alastair Rae licensed under CC BY-ND 2.0.

Photo by Hans Hillewaert licensed under CC BY-ND 2.0.

As you can probably guess by its strange appearance, the taxonomic affinity of this strange parasite has been the subject of much debate. For a long time, many botanists placed it in the family Balanophoraceae but more recent genetic work suggests it belongs in its own family, Cynomoriaceae. It is the only genus within that family but interestingly enough, Cynomoriaceae is located within the order Saxifragales, somewhere near Crassulaceae, making it a distant relative of stonecrops like sedum. No matter where its located on the tree of life, Cynomorium coccineum is surely one of the strangest plants on Earth.

Photo Credits: [1] [2]

Further Reading: [1] [2]

Opossum Pollination of a Peculiar Parasite

Floral traits can provide us with insights into the types of pollinators most suited for the job. For many flowering plants, the relationship is relatively easy to understand, but check out the flowers of Scybalium fungiforme. You would be completely excused for not even realizing that these bizarre structures belonged to a plant. The anatomy of those flowers would leave most of asking “what on Earth do they attract?” The answer to this are opossums!

Scybalium fungiforme hails from a peculiar family of parasitic plants called Balanophoraceae and is native to the Atlantic forests of Brazil. Members of this family can be found in tropical regions around the globe and all of them are obligate root holoparasites. Essentially this means that all one ever sees of these plants are their strange flowers. The rest of the plant lives within the vascular system of a host plant’s roots.

The adorable big-eared opossums (Didelphis aurita).

Scybalium fungiforme is particularly strange in that its flowers are covered in scale-like bracts. As such, accessing the flowers would be difficult for most animals. Because its strange blooms superficially resemble some marsupial and rodent pollinated Proteaceae in Australian and South Africa, predictions of a non-flying mammal pollination syndrome were about the only explanations that made sense. Now, with the help of night vision cameras, this prediction has been vindicated.

They key to this unique pollination syndrome lies in those bracts and an interesting aspect of opossum anatomy. Until the scale-like bracts are removed, not much is able to access the floral parts inside. Luckily big-eared opossums (Didelphis aurita) come equipped with opposable toes on their back feet. Upon locating the flowers of S. fungiforme, the opossum uses its back feet to remove the bracts. This unveils a bounty of nectar within. As the opossum feeds, its furry little snout gets covered in pollen. When the opossum visits subsequent flowers throughout the night, pollination is achieved.

Floral visitors of Scybalium fungiforme. b) The big-eared opossum, Didelphis aurita drinking nectar on a plant with five inflorescences (one male and four females). c) The montane grass mouse, Akodon montensis, visiting a plant with about 10 inflorescences and drinking nectar on a female one. d) The Violet-capped Woodnymph hummingbird, Thalurania glaucopis visiting a male and e) a female inflorescence. f) detail of an A. angulata wasp manipulating a male flower to eat pollen. g) Agelaia angulate visiting a female inflorescence with the head inserted among flowers to reach the nectar secreted in the inflorescence receptaculum.

Interestingly, activity doesn’t end when the opossums are done. Enough nectar often remains by the next day that a suite of other animals come to pay a visit to these strange blooms. Day time visitation of S. fungiforme consisted largely of wasps, bees, and even a mouse or two. Researchers were also lucky enough to witness Violet-capped Woodnymph hummingbirds (Thalurania glaucopis) repeatedly visit the flowers for a sip of nectar. It would appear that although the main pollinators of this strange parasite are opossums, the removal of the bracts opens up the flowers for plenty of secondary pollinators as well.

Though this is by no means the only plant to be pollinated by non-flying mammals, this pollination syndrome certainly broadens our understanding of the evolution of pollination syndromes.

Photo Credits: [1] [2] [3]

Further Reading: [1]

How radioactive carbon from nuclear bomb tests can tell us what parasitic orchids are eating

Yoania japonica. Photo by Qwert1234 licensed by CC BY-NC-SA 4.0

Historically, non-photosynthetic plants were defined as saprotrophs. It was thought that, like fungi, such plants lived directly off of decaying materials. Advances in our understanding have since revealed that parasitic plants don’t do any of the decaying themselves. Instead, those that aren’t direct parasites on the stems and roots of other plants utilize a fungal intermediary. We call these plants mycoheterotrophs (fungus-eaters). Despite recognition of this strangely fascinating relationship, we still have much to learn about what kinds of fungi these plants parasitize and where most of the nutritional demands are coming from.

It is largely assumed that most mycoheterotrophic plants are parasitic on mycorrhizal fungi. This would make them indirect parasites on other photosynthetic plants. The mycorrhizal fungi partner with photosynthetic plants, exchanging soil nutrients for carbon made by the plant during photosynthesis. However, this is largely assumed rather than tested. New research out of Japan has shown a light on what is going on with some of these parasitic relationships and the results are a bit surprising. What’s more, the methods they used to better understand these parasitic relationships are pretty clever to say the least.

Cyrtosia septentrionalis Photo by Qwert1234 licensed by CC BY-NC-SA 4.0

Photosynthesis involves the uptake of and subsequent breakdown of CO2 from the atmosphere. The carbon from CO2 is then used to build carbohydrates, which form the backbone of most plant tissues. Not all carbon is created equal, however, and by looking at ratios of different carbon isotopes in living tissues, scientists can better understand where the carbon came from. For this research, scientists utilized an isotope of carbon called 14C.

Eulophia zollingeri photo by Vinayraja licensed by CC BY-NC-SA 3.0

14C is special because it is not as common in our atmosphere as other isotopes of carbon such as 12C and 13C. One of the biggest sources of 14C in our atmosphere were nuclear bomb explosions. From the 1950’s until the Partial Nuclear Test Ban in 1963, atomic bomb tests were a regular occurrence. During that time period, the concentration of 14C in our atmosphere greatly increased. Any organism that was fixing carbon into its tissues during that span of time will contain elevated levels of 14C compared to the other carbon isotopes. Alternatively, anything fixing carbon today, say via photosynthesis, will have considerably reduced levels of 14C in its tissues.

Gastrodia elata Photo by Qwert1234 licensed by CC BY-NC-SA 4.0

By looking at the ratios of 14C in the tissues of parasitic plants, scientists reasoned that they could assess the age of the carbon being utilized. If more 14C was present, the source of the carbon could not come from today’s atmosphere and therefore not from recent photosynthesis. Instead, it would have to come from older sources like decaying wood of long-dead trees. In other words, if parasitic plants were high in 14C, then the scientists could reasonably conclude that they were parsitizing wood-decaying saprotrophic fungi. If the plants were high in 12C or 13C, then they could conclude that they were partnering with mycorrhizal fungi instead, which were obtaining carbon from present-day photsynthesis.

The researchers looked at 10 different species of parasitic plants across Japan, most of which were orchids. They analyzed their tissues and ran analyses on the carbon molecules within. What they found is that 6 out of the 10 plants contained much higher levels of 12C and 13C in their tissues, which points to mycorrhizal fungi as their host. However, for the 4 remaining species (Gastrodia elata, Cyrtosia septentrionalis, Yoania japonica and Eulophia zollingeri), the ratios of 14C were considerably higher, meaning their host fungi were eating dead wood, not partnering with photosynthetic plants near by.

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Indeed, it appears that at least some mycoheterotrophic plants are benefiting from saprotrophic rather than mycorrhizal fungi. Those early assumptions into the livelihood of such plants were not as far off the mark after all. This is very exciting research that opens the door to a much deeper understanding of some of the strangest plants on our planet.

LEARN MORE ABOUT MYCOHETEROTROPHIC PLANTS IN EPISODE 234 OF THE IN DEFENSE OF PLANTS PODCAST

Photo Credits: [1] [2] [3] [4] [5]

Further Reading: [1] [2]

Mutant Orchids Have a lot to Teach Us About Parasitic Plants

A) Albino and (B) green individual of Goodyera velutina.

The botanical world is synonymous with the idea of photosynthesis. Plants take in carbon dioxide and water and utilize light to make their own food. However, not all plants make a living this way. There are many different species of plants that have evolved a parasitic lifestyle to one degree or another. Some of my favorites are those that parasitize mycorrhizal fungi. We call these plants “mycoheterotrophs” and they are fascinating to say the least. Orchids are especially prone to this strategy, with over 1% of all known species having completely lost the ability to photosynthesize.

Our knowledge of the mycoheterotrophic strategy is fragmentary at best. We still don’t fully understand things like how the plants obtain what they need from the fungus nor how they are able to maintain their parasitic lifestyle without the fungus catching on and rejecting the one-sided partnership. This is not to say we know nothing. In fact, as technologies advance, we are unlocking at least some of the mysteries of mycoheterotrophic plants. Some of the best advances come from studying mutant, albino orchids. To understand how, we have to take a closer look at the “average” orchid lifestyle.

Orchids in general make great candidates for understanding the evolution of mycoheterotrophy because all of them start their lives as parasites. Orchids produce some of the smallest seeds in the plant kingdom and without the help of mycorrhizal fungi, they would never be able to germinate. For much of their early life, orchids rely on fungi to provide them with both their mineral and carbohydrate needs. Only after the orchids are large enough to grow leaves will most of them start to give back to their fungal partners in the form of carbohydrates generated from photosynthesis.

Still, many orchids never fully let go of this parasitic lifestyle. This is especially true for orchids living under dense forest canopies. With light in limited supply, many orchids adopt a mixotrophic lifestyle. Essentially this means that although they actively photosynthesize, they nonetheless rely on fungi to provide them with both carbohydrates and minerals. Mixotrphy is likely the most wide-spread orchid strategy and it has been hypothesized that it is also the first step along the path to becoming fully parasitic. This is where the mutant orchids enter the equation.

(A) Albino and (B) green individuals of Epipactis helleborine

Every once in a while, some orchids will germinate and grow into albino versions of their species. Without the ability to produce chlorophyll, these mutants should be destined for a quick death. Such is not the case for many of these orchids. Albino orchids often go on to live full lives, growing and flowering just like their photosynthetic progenitors. Although they do exhibit signs of reduced fitness, the fact that they are able to live at all brings up a lot of questions ready for science to tackle.

Recent investigations into the lives of these albino mutants has revealed some interesting insights into how mycoheterotrophy may have evolved in the first place. By studying the fungal partners of both healthy plants and the albinos, researchers have been able to demonstrate that albinos are doing things a bit differently than their photosynthetic parents. Using isotopes of carbon and nitrogen, scientists are discovering that the albinos have switched their interaction with the fungi in such a way that they more resemble fully mycoheterotrophic orchid species. This is done despite the fact that both albinos and their fully functional parents associate with the same guild of mycorrhizal fungi.

Another interesting difference between albinos and their photosynthetic parents is the fact that the genes involved both antioxidant metabolism and metabolite transfer (mainly carbon in this case) were more active in the albinos than they were in functioning plants. The uptick in gene functioning related to antioxidant metabolism suggests that the mutant plants are undergoing greater oxidative stress than their functional parents. This may have something to do with how the albinos are able to obtain nutrients from their fungal partners. It is thought that mycoheterotrophs actively digest parts of the fungi, which allows them to access the carbon and minerals they need to survive. This process exposes their cells to reactive oxygen compounds that can be very damaging. Antioxidants would help to reduce such damage.

The uptick in genes associated with metabolite transfer was more surprising because it suggests that despite being parasites, the plants are actively transferring substances back to the fungi. It has long been assumed that mycoheterotrophy was a one way street, with fungi transferring nutrients to plants only. These genes now suggest that, at least in some species, such transfer is a two-way street. The exact nature of this two-way transfer remains a mystery and certainly brings up many more questions that must be asked before we can better understand this relationship.

All of this is not to say that such albino mutants are fruitful “next steps” in the evolution of these species. Far from it, in fact. Two things that most albino orchid variants have in common is the fact that they are rare and, of those that have been studied, produce far fewer seeds. There are a lot of anatomical and physiological differences between true mycoheterotrophic species and albino variants and it appears that without those anatomical adaptations, the albinos are a lot less fit than their photosynthetic parents. As authors Selosse and Roy put it:

“non-chlorophyllous variants are likely to represent unique snapshots of failed transitions from mixotrophy to mycoheterotrophy. They are ecological equivalents to mutants in genetics, that is, their dysfunctions might suggest what makes mycoheterotrophy successful. Although their determinism remains unknown, they offer fascinating models for comparing the physiology of mixo- and mycoheterotrophs within similar genetic backgrounds.”

Mutants are strange indeed but with the right kinds of questions and approaches, they have a lot to teach us about ecology, evolution, and life at large.

Photo Credits: [1] [2]

Further Reading: [1] [2] [3]

The Smallest of the Giants

Photo by Edwino S. Fernando [source]

There are a lot of cool ways to discover a new species but what about tripping over one? That is exactly how Rafflesia consueloae was found. Researchers from the University of the Philippines Los Baños were walking through the forest back in 2014 when one of them tripped over something. To their surprise, it was the bloom of a strange parasitic plant.

This was an exciting discovery because it meant that that strange family of holoparasitic plants called Rafflesiaceae just got a little bit bigger. Rafflesiaceae is famous the world over for the size of its flowers. Whereas the main body of plants in this family consists of tiny thread-like structures living within the tissues of forest vines, the flowers of many are huge. In fact, with a flower 3 feet (1 meter) in diameter, which can weigh as much as 24 lbs. (11 kg), Rafflesia arnoldii  produces the largest flower on the planet. This new species of Rafflesia, however, is a bit of a shrimp compared to its cousins.

In fact, R. consueloae produces the smallest flowers of the genus. Of the individuals that have been found, the largest flower clocked in at 3.83 inches (9.37 cm) in diameter. Needless to say, this was an exciting discovery and those responsible for it quickly set about observing the plant in detail. Cameras were set up to monitor flower development as well as to keep track of any animals that might pay it a visit. It turns out that, like its cousins, R. consueloae appears to be a specialist parasite on a group of vines in the genus Tetrastigma.

One of the unique characteristics of R. consueloae, other than its size, is the fact that its flowers don’t seem to produce any noticeable scent. This is a bit odd considering that its cousins are frequently referred to as “corpse flowers” thanks to the fact that they both look and smell like rotting meat. That is not to say that this species produces no scent at all. In fact, researchers noted that the fruits of R. consueloae smell a bit like coconut.

Its discoverers were quick to note that the discovery of such a strange parasitic plant in this particular stretch of forest is exciting because of the state of disrepair the forest is in. This region has suffered heavily from deforestation and fragmentation and it has long been thought that such specialized parasites like those in the genus Rafflesia could not persist after logging. As such, this discovery offers at least some hope that they may not be as sensitive as we once thought. Still, that does not mean that R. consueloae is by any means secure in its future.

To date, R. consueloae has only been found growing in two localities in Pantabangan, Phillippines. Though it is possible that more populations will be found growing elsewhere, its limited distribution nonetheless places it at high risk for extinction. Further habitat loss and the potential for anthropogenic forest fires are considerable threats to these plants and the hosts they simply can’t live without.

Despite plenty of observation, no one is quite sure how this species manages to reproduce successfully. Individual flowers are said to be either male or female but without a scent, its hard to say who or what pollinates them. Similarly, it still remains a mystery as to how R. consueloae (or any of its relatives for that matter) accomplish seed dispersal. Some small mammals were seen feeding on fruits but what happens after that is anyone’s guess. It seems like the various Rafflesiaceae still have many mysteries to be solved.

Photo Credit: [1]

Further Reading: [1]

Is Love Vine Parasitizing Wasps?

Photo by David Eickhoff licensed under CC BY 2.0

No, that's not dodder (Cuscuta sp.), its love vine (Cassytha filiformis), a member of the same family as the avacados in your kitchen (Lauraceae). It is a pantropical parasite that makes its living stealing water and nutrients from other plants. To do so, it punctures their vascular tissues with specialized structures called "haustoria." Amazingly, a recent observation made in Florida suggests that this botanical parasite may also be taking advantage of other parasites, specifically gall wasps.

Gall wasps are also plant parasites. They lay their eggs in developing plant tissues and the larvae release compounds that coax the plant to form nutrient-rich galls packed full of starchy goodness. Essentially you can think of galls as edible nursery chambers for the wasp larvae. While looking for galls on sand live oak (Quercus geminata) growing in southern Florida, Dr. Scott Egan and his colleagues noticed something odd. A small vine seemed to be attaching itself to the galls.

Love vine draping a host plant. Photo by Forest & Kim Starr licensed under CC BY 3.0

The vine in question was none other than love vine and they were attached to galls growing on the underside of the oak leaves. What is strange is that, of all of the places that love vine likes to attach itself to its host (new stems, buds, petioles, and on the top and edge of leaves), the only time this vine showed any "interest" in the underside of oak leaves was when galls were present. Obviously this required further investigation.

The team discovered that at least two different species of gall wasps were being parasitized by love vine - one that produces small, spherical galls on the underside of oak leaves and one that forms large, multi-chambered galls on oak stems. Upon measuring the infected and uninfected galls, the team discovered that there were significant differences that could have real ecological significance.

(A) Cassytha filiformis vine attaching haustoria to a leaf gall induced by the wasp Belonocnema treatae on the underside of their host plant, Quercus geminata. (B) Labeled graphic of insect gall, parasitic vine, and vine haustoria. (C) Box plots of leaf gall diameter for unparasitized galls (control) and galls that have been parasitized by C. filiformis. (D) Proportion of B. treatae leaf galls that contained a dead ‘mummified’ adult for unparasitized galls (control) and galls that have been parasitized by the vine C. filiformis. [SOURCE]

For the spherical gall wasp, infected galls tended to be much larger, however, the team feels that this may actually be due to the fact that the vine "prefers" larger galls. Astonishingly, larvae living in the infected galls were 45% less likely to survive. For the multi-chambered gall wasp, infection by love vine was associated with a 13.5% decrease in overall gall size. They suggest this is evidence that love vine is having net negative impacts on these parasitic wasps.

Subsequent investigation revealed that these wasps were not alone. In total, the team found love vine attacking the galls of at least two other wasps and one species of gall-making fly (though no data were reported for these cases). To be sure that love vine was in fact parasitizing these galls, they needed to have a closer look at what the vine was actually doing.

Figure S2. (A) Cassytha filiformis vine attaching haustoria to a leaf gall induced by the wasp Callirhytis quercusbatatoides on the stem of their host plant, Quercus geminata. (B) Labeled graphic of insect gall, parasitic vine, and vine haustoria on C. quercusbatatoides. (C) Exemplar of parasitic vine wrapping tightly around the stem directly proximate to a gall induced by the wasp Disholcaspis quercusvirens on Q. geminata. (D) Field site where love vine, C. filiformis, is attacking the sand live oak, Q. geminata, and many of the gall forming wasps on the same host plant. [SOURCE]
 

Dissection of the galls revealed that the haustoria were plugged into the gall itself, not the wasp larvae. However, because the larvae simply cannot develop without the nutrients and protection provided by the gall, Eagan and his colleagues conclude that these do indeed represent a case of a parasite being parasitized by another parasite.

At this point, the next question that must be asked is how common is this in love vine or, for that matter, across all other parasitic plants that utilize haustoria. Considering that parasites of parasites are nothing new in the biosphere, it is a safe bet that this will not be the last time this phenomenon is discovered.

Photo Credits: [1] [2] [3] [4]

Further Reading: [1]

Parasitic Plant Rediscovered After a 151 Year Absence

Extinction is a hard status to confirm for many types organisms. Whereas discovering a new species requires finding only a single individual, declaring one extinct requires knowing that there are no individuals left at all. This is especially true when organisms live cryptic lifestyles, a point recently made quite apparent by the rediscovery of a small parasitic plant known scientifically ask Thismia neptunis.

Thismia neptunis is a type of parasite called a mycoheterotroph, which means it makes its living by parasitizing mycorrhizal fungi in the soil. It obtains all of its needs in this way. As such, it produces no leaves, no chlorophyll, and really nothing that would readily identify it outright as a plant. All one would ever see of this species are its bizarre flowers that look more like a sea anemone than anything botanical. Like most mycoheterotrophs, when not in flower it lives a subterranean lifestyle.

The original drawing of Thismia neptunis (from Beccari 1878).

This is why finding them can be so difficult. Even when you know where they are supposed to grow, infrequent flowering events can make assessing population numbers extremely difficult. Add to this the fact that Thismia neptunis is only known from a small region of Borneo near Sarawak where it grows in the dense understory of hyperdiverse Dipterocarp forests. It was first found and described back in 1866 but was not seen again for 151 years. To be honest, it is hard to say whether or not most folks were actively searching.

Regardless, after a 151 year absence, a team of botanists recently rediscovered this wonderful little parasite flowering not too far from where it was originally described. Though more study will be needed to flesh out the ecology of this tiny parasitic plant, the team was fortunate enough to witness a few tiny flies flitting around within the flower tube. It could very well be that these odd flowers are pollinated by tiny flies that frequent these shaded forest understories.

As exciting as this rediscovery is, it nonetheless underscores the importance of forest conservation. The fact that no one had seen this plant in over a century speaks volumes about how little we understand the diversity of such biodiverse regions. The rate at which such forests are being cleared means that we are undoubtedly losing countless species that we don't even know exist. Forest conservation is a must. 

Click here to support forest conservation efforts in Borneo. 

Photo Credit and Further Reading: [1]

How a Giant Parasitic Orchid Makes a Living

Photo by mutolisp licensed under CC BY-NC-SA 2.0

Imagine a giant vine with no leaves and no chlorophyll scrambling over decaying wood and branches of a warm tropical forest. As remarkable as that may seem, that is exactly what Erythrorchis altissima is. With stems that can grow to upwards of 10 meters in length, this bizarre orchid from tropical Asia is the largest mycoheterotrophic plant known to science.

Mycoheterotrophs are plants that obtain all of their energy needs by parasitizing fungi. As you can probably imagine, this is an extremely indirect way for a plant to make a living. In most instances, this means the parasitic plants are stealing nutrients from the fungi that were obtained via a partnership with photosynthetic plants in the area. In other words, mycoheterotrophic plants are indirectly stealing from photosynthetic plants.

In the case of E. altissima, this begs the question of where does all of the carbon needed to build a surprising amount of plant come from? Is it parasitizing the mycorrhizal network associated with its photosynthetic neighbors or is it up to something else? These are exactly the sorts of questions a team from Saga University in Japan wanted to answer.

Photo by mutolisp licensed under CC BY-NC-SA 2.0

All orchids require fungal partners for germination and survival. That is one of the main reasons why orchids can be so finicky about where they will grow. Without the fungi, especially in the early years of growth, you simply don't have orchids. The first step in figuring out how this massive parasitic orchid makes its living was to identify what types of fungi it partners with. To do this, the team took root samples and isolated the fungi living within.

By looking at their DNA, the team was able to identify 37 unique fungal taxa associated with this species. Most surprising was that a majority of those fungi were not considered mycorrhizal (though at least one mycorrhizal species was identified). Instead, the vast majority of the fungi associated with with this orchid are involved in wood decay.

Stems climbing on fallen dead wood (a) or on standing living trees (b). A thick and densely branched root clump (c) and thin and elongate roots (d) [Source]

To ensure that these wood decay fungi weren't simply partnering with adult plants, the team decided to test whether or not the wood decay fungi were able to induce germination of E. altissima seeds. In vitro germination trials revealed that not only do these fungi induce seed germination in this orchid, they also fuel the early growth stages of the plant. Further tests also revealed that all of the carbon and nitrogen needs of E. altissima are met by these wood decay fungi.

These results are amazing. It shows that the largest mycoheterotrophic plant we know of lives entirely off of a generalized group of fungi responsible for the breakdown of wood. By parasitizing these fungi, the orchid has gained access to one of the largest pools of carbon (and other nutrients) without having to give anything back in return. It is no wonder then that this orchid is able to reach such epic proportions without having to do any photosynthesizing of its own. What an incredible world we live in!

Photo by mutolisp licensed under CC BY-NC-SA 2.0

Photo Credits: [1] [2]

Further Reading: [1]

On the Ecology of Krameria

Photo by Stan Shebs licensed under CC BY-SA 3.0

There is something satisfying about saying "Krameria." Whereas so many scientific names act as tongue twisters, Krameria rolls of the tongue with a satisfying confidence. What's more, the 18 or so species within this genus are fascinating plants whose lifestyles are as exciting as their overall appearance. Today I would like to give you an overview of these unique parasitic plants.

Commonly known as rhatany, these plants belong to the family Krameriaceae. This is a monotypic clade, containing only the genus Krameria. Historically there has been a bit of confusion as to where these plants fit on the tree of life. Throughout the years, Krameria has been placed in families like Fabaceae and Polygalaceae, however, more recent genetic work suggests it to be unique enough to warrant a family status of its own. 

Regardless of its taxonomic affiliation, Krameria is a wonderfully specialized genus of plants with plenty of offer the biologically curious among us. All 18 species are shrubby, though at least a couple species can sometimes barely qualify as such. They are a Western Hemisphere taxon with species growing native as far south as Paraguay and Chile and as far north as Kansas and Colorado. They generally inhabit dry habitats.

Photo by Stan Shebs licensed under CC BY-SA 3.0

As I briefly mentioned above, most if not all of the 18 species are parasitic in nature. They are what we call "hemiparasites" in that despite stealing from their hosts, they are nonetheless fully capable of photosynthesis. It is interesting to note that no one (from what I have been able to find) has yet been able to raise these plants in captivity without a host. It would seem that despite being able to photosynthesize, these plants are rather specialized parasites. 

That is not to say that they have evolved to live off of a specific host. Far from it actually. A wide array of potential hosts, ranging from annuals to perennials, have been identified. What I find most remarkable about their parasitic lifestyle is the undeniable advantage it gives these shrubs in hot, dry environments. Research has found that despite getting a slow start on growing in spring, the various Krameria species are capable of performing photosynthesis during extremely stressful periods and for a much longer duration than the surrounding vegetation. 

Photo by mlhradio licensed under CC BY-NC 2.0

The reason for this has everything to do with their parasitic lifestyle. Instead of producing a long taproot to reach water reserves deep in the soil, these shrubs invest in a dense layer of lateral roots that spread out in the uppermost layers of soil seeking unsuspecting hosts. When these roots find a plant worth parasitizing, they grow around its roots and begin taking up water and nutrients from them. By doing this, Krameria are not limited by what water or other resources their roots can find in the soil. Instead, they have managed to tap into large reserves that would otherwise be locked away inside the tissues of their neighbors. As such, the Krameria do not have to worry about water stress in the same way that non-parasitic plants do. 

Photo by Stan Shebs licensed under CC BY-SA 3.0

By far the most stunning feature of the genus Krameria are the flowers. Looking at them it is no wonder why they have been associated with legumes and milkworts. They are beautiful and complex structures with a rather specific pollination syndrome. Krameria flowers produce no nectar to speak of. Instead, they have evolved alongside a group of oil-collecting bees in the genus Centris.

One distinguishing feature of Krameria flowers are a pair of waxy glands situated on each side of the ovary. These glands produce oils that female Centris bees require for reproduction. Though Centris bees are not specialized on Krameria flowers, they nonetheless visit them in high numbers. Females alight on the lip and begin scraping off oils from the glands. As they do this, they inevitably come into contact with the stamens and pistil. The female bees don't feed on these oils. Instead, they combine it with pollen and nectar from other plant species into nutrient-rich food packets that they feed to their developing larvae.  

Photo by João Medeiros licensed under CC BY 2.0

Following fertilization, seeds mature inside of spiny capsules. These capsules vary quite a bit in form and are quite useful in species identification. Each spine is usually tipped in backward-facing barbs, making them excellent hitchhikers on the fur and feathers of any animal that comes into contact with them.  

Photo Credits: [1] [2] [3] [4] [5]

Further Reading: [1] [2] [3] [4]

Cockroaches & Unexpected Partnerships

Photo by Alpsdake licensed under CC BY-SA 4.0

Say "cockroach" and most people will start to squirm. These indefatigable insects are maligned the world over because of a handful of species that have settled in quite nicely among human habitats. The world of cockroaches is far more diverse than most even care to realize, and where they occur naturally, these insects provide important ecological services. For instance, over the last decade or so, researchers have added pollination and seed dispersal to the list of cockroach activities. 

That's right, pollination and seed dispersal. It may seem odd to think of roaches partaking in such interactions but a study published in 2008 provides some of the first evidence that roaches are doing more with plants than eating their decaying tissues. After describing a new species of Clusia in French Guiana, researchers set out to investigate what, if anything, was pollinating it. The plant was named Clusia sellowiana and its flowers emitted a strange scent. 

Cockroach pollinating C. sellowiana. [SOURCE]

The source of this scent was the chemical acetoin. It seemed to be a rather attractive scent as a small variety of insects were observed visiting the flowers. However, only one insect seemed to be performing the bulk of pollination services for this new species - a small cockroach called Amazonia platystylata. It turns out that the roaches are particularly sensitive to acetoin and although they don't have any specific anatomical features for transferring pollen, their rough exoskeleton nonetheless picks up and deposits ample amounts of the stuff. 

It would appear that C. sellowiana has entered into a rather specific relationship with this species of cockroach. Although this is only the second documentation of roach pollination, it certainly suggests that more attention is needed. This Clusia isn't alone in its interactions with cockroaches either. As I hinted above, roaches can now be added to the list of seed dispersers of a small parasitic plant native to Japan. 

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 (A) M. humile fruit showing many minute seeds embedded in the less juicy pulp. (B) Fallen fruits. (C) Blattella nipponica feeding on the fruit. (D) Cockroach poop with seeds. (E) Stained cockroach-ingested seeds. [SOURCE]

Monotropastrum humile looks a lot like Monotropa found growing in North America. Indeed, these plants are close cousins, united under the family Ericaceae. Interestingly enough, it was only recently found that camel crickets are playing an important role in the seed dispersal of this species. However, it looks like they aren't the only game in town. Researchers have also found that a forest dwelling cockroach called Blattella nipponica serves as a seed disperser as well. 

The roaches were observed feeding on the fruits of this parasitic plant, consuming pulp and seed alike. What's more, careful observation of their poop revealed that seeds of M. humile passed through the digestive tract unharmed. Cockroaches can travel great distances and therefore may provide an important service in distributing the seeds of a rather obscure parasitic plant. To think that this is an isolated case seems a bit naive. It seems to me like we should pay a little more attention to what cockroaches are doing in forests around the world. 

Photo Credits: [1] [2] [3]

Further Reading: [1] [2]

Are Crickets Dispersing Seeds of Parasitic Plants?

[SOURCE]

Parasitic plants lead unique lifestyles. Many have foregone photosynthesis entirely by living off fungi or their photosynthetic neighbors. Indeed, there are many anatomical and physiological adaptations that are associated with making a living parasitically. Whether they are full parasites or only partial, one thing that many parasitic plants have in common are tiny, dust-like seeds. Their reduced size and thin seed coats are generally associated with wind dispersal, however, there are always exceptions to the rule. Recent evidence has demonstrated that a handful of parasitic plants have evolved in response to a unique seed dispersal agent - camel crickets.

A research team based out of Japan recently published a paper describing a rather intriguing seed dispersal situation involving three species of parasitic plants (Yoania amagiensis - Orchidaceae, Monotropastrum humile - Ericaceae, and Phacellanthus tubiflorus - Orobanchaceae). These are all small, achlorophyllous herbs that either parasitize trees directly through their roots or they parasitize the mycorrhizal fungi associated with said trees. What's more, each of these species are largely inhabitants of the dense, shaded understory of rich forests.

These sorts of habitats don't lend well to wind dispersal. The closed forest canopy and dense understory really limits wind flow. It would appear that these three plant species have found away around this issue. Each of these plants invest in surprisingly fleshy fruits for their parasitic lifestyle. Also, their seeds aren't as dust-like as many of their relatives. They are actually very fleshy. This is odd considering the thin margins many parasitic plants live on. Any sort of investment in costly tissues must have considerable benefits for the plants if they are to successfully get their genes into the next generation.

Fleshy fruits like this are usually associated with a form of animal dispersal called endozoochory. Anyone that has ever found seed-laden bird poop understands how this process works. Still, simply getting an animal to eat your seeds isn't necessarily enough for successful dispersal. Seeds must survive their trip through the gut and come out the other end relatively in tact for the process to work. That is where a bit of close observation came into play.

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[SOURCE]

After hours of observation, the team found that the usual frugivorous suspects such as birds and small mammals showed little to no interest in the fruits of these parasites. Beetles were observed munching on the fruits a bit but the real attention was given by a group of stumpy-looking nocturnal insects collectively referred to as camel crickets. Again, eating the fruits is but one step in the process of successful seed dispersal. The real question was whether or not the seeds of these parasites survived their time inside either of these insect groups. To answer this question, the team employed feeding trials.

They compared seed viability by offering up fruits to beetles and crickets both in the field and back in the lab. Whereas both groups of insects readily consumed the fruits and seeds, only the crickets appeared to offer the greatest chances of a seed surviving the process. Beetles never pooped out viable seeds. The strong mandibles of the beetles fatally damaged the seeds. This was not the case for the camel crickets. Instead, these nocturnal insects frequently pooped out tens to hundreds of healthy, viable seeds. Considering the distances the crickets can travel as well as their propensity for enjoying similar habitats as the plants, this stacks up to potentially be a beneficial interaction. 

The authors are sure to note that these results do not suggest that camel crickets are the sole seed dispersal agents for these plants. Still, the fact that they are effective at moving large amounts of seeds is tantalizing to say the least. Taken together with other evidence such as the fact that the fruits of these plants often give off a fermented odor, which is known to attract camel crickets, the fleshy nature of their fruits and seeds, and the fact that these plants present ripe seed capsules at or near the soil surface suggests that crickets (and potentially other insects) may very well be important factors in the reproductive ecology of these plants.

Coupled with previous evidence of cricket seed dispersal, it would appear that this sort of relationship between plants and crickets is more widespread than we ever imagined. It is interesting to note that relatives of both the plants in this study and the camel crickets occur in both temperate and tropical habitats around the globe. We very well could be overlooking a considerable component of seed dispersal ecology via crickets. Certainly more work is needed.

Photo Credits: [1]

Further Reading: [1] [2]

Broomrape: What's in a Name?

Dr. Reuven Jacobsohn, Agricultural Research Organization, Bugwood.org
licensed under a Creative Commons Attribution-Noncommercial 3.0 License.

One can turn a lot of heads by speaking publicly of the plants in the family Orobanchaceae. This interesting and often beautiful parasitic plant family is collectively referred to as the broomrape family. Species with common names like “naked broomrape” and “spiked broomrape” can really make a casual plant conversation turn sour in no time.

Despite how heinous the name sounds, its origin is a bit more innocent. I have really grown to appreciate etymology. Learning the hidden meaning behind the words we utilize for taxonomy can be a lot of fun. It can also teach you a little bit more about the species itself. 

In this context, rape stems from the Latin word “rapum,” which roughly translates to “tuber” or “turnip.” Broom is an English word that, in this context, refers to a shrubby plant related to vetch, which is often parasitized by broomrapes. So, the literal meaning of broomrape is something akin to “broom tuber.” In other words, they are plants growing on the roots of vetch. So, yea, the more you know…

Further Reading: [1]

Photo by Ian Boyd licensed under CC BY-NC 2.0

Photo by Martin Heigan licensed under CC BY-NC-ND 2.0

Photo by Park Ranger licensed under CC BY-NC-SA 2.0

Photo by mpaola_andreoni licensed under CC BY-NC-ND 2.0

A Peculiar Parasite at Berkeley

Parasitic plants are fascinating. I never pass up an opportunity to meet them. On a recent trip to California, my host for the day mentioned that something funny was growing in a patch of ivy on the Berkeley Campus. I had to know what it was. We took a detour from our intended rout and there, growing underneath a pine tree in a dense patch of ivy were these odd purple and brown stalks. This was definitely a parasitic plant.

The plant in question was the ivy broomrape (Orobanche hederae). As both its common and scientific name suggests, it is a parasite on ivy (Hedera spp.). As you can probably guess based on the identity of its host, ivy broomrape is not native to North America. In fact, the population we were looking at is the only known population of this plant you will find in the Americas. How it came to be in that specific location is a bit of a mystery but the proximity to the life sciences building suggests that this introduction might have been intentional. Personally I am quite alright with this introduction as it is parasitizing one of the nastier invasive species on this continent.

The ivy broomrape starts its life as a tiny seed. Upon germination, the tiny embryo sends out a thin thread-like filament that spirals out away from the embryo into the surrounding soils. The filament is looking for the roots of its host. Upon contact with ivy roots, the filament penetrates xylem tissues. The ivy broomrape is now plugged in, receiving all of its water, nutrient, and carbohydrate needs from the ivy. At this point the embryo begins to grow larger, throwing out more and more parasitic roots in the process. These locate more and more ivy roots until the needs of the ivy broomrape are met. Of course, all of this is going on underground.

Only when the ivy broomrape has garnered enough energy to flower will you see this plant. A stalk full of purple tinged, tubular flowers emerges from the ground. At this point its membership in the family Orobanchaceae is readily apparent. Like all members of this family, its parasitic lifestyle is so complete that it is beginning to lose genes for the production of chlorophyll and Rubisco, all things we generally associate with plants. This is why I love parasites so much. Not only are their ecological impacts bewilderingly complex, their evolutionary histories are such a departure from the norm. I will never tire of appreciating such species and I am happy to have met yet another awesome member of this group.

Further Reading:
http://onlinelibrary.wiley.com/doi/10.1111/j.1469-8137.1925.tb06671.x/pdf

http://cat.inist.fr/?aModele=afficheN&cpsidt=4107447

Meet Virginia Pennywort

Meet the pennywort gentian (Obolaria virginica). It is a plant of the southeast with its most northerly distribution being around Pennsylvania. I am a little obsessed with gentians so finding this plant is always a special treat. My first encounter left me a bit perplexed by its overall appearance, which is very compact. The leaves and flowers all seemed to be mashed together, competing for space. 

Its small stature and dark coloration cause it to blend in surprisingly well with the forest floor. You often don't see it until you are right on top of one. Something seems to be working well for the Virginia pennywort because once you find one, you usually find many more. Oddly enough, I most frequently see this species in its highest abundance on the side of well-trafficked trails. Add to that its highly reduced leaf area and you have a few traits that usually get me thinking about parasitic plants. Anecdotally speaking, I often find parasitic plants growing near foot traffic. If I had to guess, I would say that it has something to do with root damage, however, I have no data to support such claims. That being said, the literature suggests I wasn't wrong in my suspicions.  

The roots of the Virginia pennywort are described as "coralloid", meaning they take on a structure reminiscent of some corals. This is usually a trait exhibited by species whose roots are closely associated with microbes such as cyanobacteria or certain fungi. Indeed, the roots of the Virginia pennywort are often infested with arbuscular mycorrhizae. Additionally, there is some molecular evidence to suggest that this species is at least partially mycoheterotrophic, meaning it gets some at least some of its nutrients parasitically from said mycorrhizal fungi. Isotope analysis demonstrated that the tissues of the Virginia pennywort were more enriched with isotopes of carbon than the surrounding vegetation.

It is a really neat plant to find. If you do, make sure to take some time with it and get down on its level for a closer look. You won't be disappointed!

Further Reading:
http://www.amjbot.org/content/97/8/1272.short

http://plants.usda.gov/java/profile?symbol=obvi

Newly Discovered Orchid Doesn't Bother With Photosynthesis or Opening Its Flowers

Photo by Suetsugu Kenji [SOURCE]

A new species of orchid has been discovered on the small Japanese island of Kuroshima. Though not readily recognized as an orchid, it nonetheless resides in the tribe Epidendroideae. Although the flowers of its cousins are often quite showy, this orchid produces small brown blooms that never open. What's more, it has evolved a completely parasitic lifestyle. 

The discovery of this species is quite exciting. The flora of Japan has long thought to be well picked over by botanists and ecologists alike. Finding something new is a special event. The discovery was made by Suetsugu Kenji, associate professor at the Kobe University Graduate School of Science. This discovery was made about a year after a previous parasitic plant discovery made on another Japanese island a mere stones throw from Kuroshima.

Coined Gastrodia kuroshimensis, this interesting little parasite flies in the face of what we generally think of when we think of orchids. It is small, drab, and lives out its entire life on the shaded forest floor. Like the rest of its genus, G. kuroshimensis is mycoheterotrophic. It produces no leaves or chlorophyll, living its entire life as a parasite on mycorrhizal fungi underground. This is not necessarily bizarre behavior for orchids (and plants in general). Many different species have adopted this strategy. What was surprising about its discovery is the fact that its flowers never seem to open. 

In botany this is called "cleistogamy." It is largely believed that cleistogamy evolved as both an energy saving and survival strategy. Instead of dumping lots of energy into producing large, showy flowers to attract pollinators, that energy can instead be used for seed production and persistence. Additionally, since the flowers never open, cross pollination cannot occur. The resulting offspring share 100% of their genes with the parent plant. Although this can be seen as a disadvantage, it can also be an advantage when conditions are tough. If the parent plant is adapted to the specific conditions in which it grows, giving 100% of its genes to its offspring means that they too will be wonderfully adapted to the conditions they are born into. 

As you can probably imagine, pure cleistogamy can be quite risky if conditions rapidly change. In the face of continued human pressures and rapid climate change, cleistogamy as a strategy might not be so good. That is one reason why the discovery of this bizarre little orchid is so interesting. Whereas most species that produce cleistogamous flowers also produce "normal" flowesr that open, this species seems to have given up that ability. Thus, G. kuroshimensis offers researchers a window into how and why this reproductive strategy evolved. 

Photo Credit: Suetsugu Kenji

Further Reading: [1]

On the Wood Rose and its Bats

Photo via Nga Manu Nature Reserve

New Zealand has some weird nature. It is amazing to see what an island free of any major terrestrial predators can produce. Unfortunately, ever since humans found their way to this unique island, the ecology has suffered. One of the most unique plant and animal interactions in the world can be found on this archipelago but for how much longer is the question.

The story starts with a species of bat. In fact, this bat is New Zealand's only native terrestrial mammal. That's right, I said terrestrial. The New Zealand lesser short-tailed bat spends roughly 40% of its time foraging for insects on the ground. It has lots of specialized adaptations that I won't go into here but the cool part is they forage in packs, stirring up insects from the leaf litter until they reach a level of feeding frenzy that I thought was only reserved for sharks or piranhas. Along with using echo location, they also have a highly developed sense of smell. This is important for our second player in this forest floor drama.

Enter Dactylanthus taylorii, the wood rose. This plant is not a rose at all but rather a member of the tropical family Balanophoraceae. More importantly, it is parasitic. It produces no chlorophyll and lives most of its life wrapped around the roots of its host tree underground. Every once in a while a small patch of flowers break through the dirt and just barely peak above the leaf litter. This give this species it's Māori name of "pua o te reinga" or "pua reinga", which translates to "flower of the underworld." The flowers emit a musky, sweet smell that attracts these ground foraging bats. The bats are one of the only pollinators left on the island. They sniff out the flowers and dine on the nectar, all the while being dusted with pollen. Recently, it has been found that New Zealand's giant ground parrot, the kakapo, is also believed to have been a pollinator of this plant. Sadly, today the kakapo exists solely on one small island of the New Zealand archipelago.

Both the wood rose and the New Zealand lesser short-tailed bat are considered at risk for extinction. When modern man came to these islands they brought with them the general suite of mammalian invasives like rats, mongoose, cats, and pigs, which are exacting a major toll on the local ecology. The plants and animals native to New Zealand have not shared an evolutionary history with such aggressive mammalian invaders and thus have no adaptations for coping with their sudden presence. The future of the wood rose, the New Zealand lesser short-tailed bat, and the kakapo, along with many other uniquely New Zealand species are for now uncertain.

Photo Credits: Joseph Dalton Hooker (1859) and Nga Manu Nature Reserve (http://www.ngamanu.co.nz/)

Further Reading:

http://bit.ly/2bBw8FT

http://bit.ly/2bKRY90

http://bit.ly/2bKpxfE

Buffalonut - A Parasitic Shrub From Appalachia

I have a hard time with shrubby species. They just don't stand out to me like herbaceous plants or giant trees. As such, my identification skills for this group of medium-sized woody plants are subpar. However, every once in a while I find something that I can't let go. Usually its a species with a trait that really stands out. This is how I came to know buffalo nut (Pyrularia pubera). Its unique inflorescence was like nothing I had ever encountered before. 

There is good reason for my unfamiliarity with this species. It is largely restricted to the core of the Appalachian Mountains, although there are records of it growing on Long Island as well. Regardless, it is not a species I grew up around. The first time I saw its flowers I was stumped. I simply couldn't place it. Luckily its unique appearance made it easy to track down. I was happy with buffalo nut for the time being but I was surprised yet again when I sat down for a chat with someone who knows woody species much better than I do. 

As it turns out, buffalo nut belongs to the sandalwood family, Santalaceae. This makes it a distant cousin of the mistletoes. Like most members of this family, buffalo nut lives a parasitic lifestyle. Although it is fully capable of photosynthesis and "normal" root behavior, under natural conditions, it parasitizes the roots of other tree species. It doesn't really seem to have a preference either. Over 60 different species hailing from 31 different families have been recorded as hosts. 

When a buffalo nut seed germinates, it starts by throwing down a taproot. Once the taproot reaches a certain depth, lateral roots are sent out in search of a host. These roots "sniff out" the roots of other species by honing in on root exudates. When a suitable root is found, the buffalo nut root will tap into its host using specialized cells called haustoria. Once connected, it begins stealing water and nutrients. Buffalo nut roots have been known to travel distances of 40 feet in search of a host, which is pretty incredible if you ask me. 

It is easy to look down on parasites. Heck, they are largely maligned as free loaders. This could not be farther from the truth. Parasites are a healthy component of every ecosystem on the planet. They are a yet another player in a system that is constantly changing. What's more, the presence of parasites can actually increase biodiversity in a system by keeping certain species from becoming too dominant. Buffalo nut should not be persecuted. Instead it should be celebrated. It is yet another species that makes the Appalachian Mountain flora so unique. 

Further Reading: [1] [2]

Rhizanthes lowii

Photo Credit: Ch'ien C. Lee - www.wildborneo.com.my/photo.php?f=cld1500900.jpg

Imagine hiking through the forests of Borneo and coming across this strange object. It's hairy, it's fleshy, and it smells awful. With no vegetative bits lying around, you may jump to the conclusion that this was some sort of fungus. You would be wrong. What you are looking at is the flower of a strange parasitic plant known as Rhizanthes lowii.

Rhizanthes lowii is a holoparasite. It produces no photosynthetic tissues whatsoever. In fact, aside from its bizarre flowers, its doesn't produce anything that would readily characterize it as a plant. In lieu of stems, leaves, and roots, this species lives as a network of mycelium-like cells inside the roots of their vine hosts. Only when it comes time to flower will you ever encounter this species (or any of its relatives for that matter).

The flowers are interesting structures. Their sole function, of course, is to attract their pollinators, which in this case are carrion flies. As one would imagine, the flowers add to their already meaty appearance a smell that has been likened to that of a rotting corpse. Even more peculiar, however, is the fact that these flowers produce their own heat. Using a unique metabolic pathway, the flower temperature can rise as much as 7 degrees above ambient. Even more strange is the fact that the flowers seem to be able to regulate this temperature. Instead of a dramatic spike followed by a gradual decrease in temperature, the flowers of R. lowii are able to maintain this temperature gradient throughout the flowering period.

Photo Credit: Ch'ien C. Lee - www.wildborneo.com.my/photo.php?f=cld1500900.jpg

There could be many reasons for doing this. Heat could enhance the rate of floral development. This is a likely possibility as temperature increases have been recorded during bud development. It could also be used as a way of enticing pollinators, which can use the flower to warm up. This seems unlikely given its tropical habitat. Another possibility is that it helps disperse its odor by volatilizing the smelly compounds. In a similar vein, it may improve the carrion mimicry. Certainly this may play a role, however, flies don't seem to have an issue finding carrion that has cooled to ambient temperature. Finally, it has also been suggested that the heat may improve fertilization rates. This also seems quite likely as thermoregulation has been shown to continue after the flowers have withered away.

Regardless of its true purpose, the combination of lifestyle, appearance, and heat producing properties of this species makes for a bizarrely spectacular floral encounter. To see this plant in the wild would be a truly special event.

Photo Credit: Ch'ien C. Lee - www.wildborneo.com.my/photo.php?f=cld1500900.jpg

Further Reading: [1] [2]