Underwater Pollinators

[SOURCE]

Modern day aquatic plants are highly derived organisms. Similar to dolphins and whales, today's aquatic plants did not originate in their watery environment. Instead, they gradually evolved from land plants living close to the water's edge. One of the biggest challenges for fully aquatic plants involves pollination. Many species overcome this hurdle by thrusting their flowers up and out of the water where there are far more pollen vectors. Others rely on water currents and a little bit of chance. For aquatic plants whose flowers open under water, water pollination, or "hydrophily", has long been the only proposed mechanism. Surely aquatic animals could not be involved in aquatic pollination. Well, a newly published study on a species of seagrass known scientifically as Thalassia testudinum suggests otherwise.

Seagrasses are ecological cornerstones in marine environments. They form vast underwater meadows and are considered one of the world's most productive ecosystems. Most seagrasses are clonal. Because of this, sexual reproduction in this group has mostly been overlooked. However, they do produce flowers that are tucked down in among their leaves. The production of flowers coupled with a surprising amount of genetic diversity have led some researchers to take a closer look at their reproduction.

A team of researchers based out of the National Autonomous University of Mexico decided to look at potential pollen vectors in Thalassia testudinum, a dominant seagrass species throughout the Caribbean and western Atlantic regions. T. tetidinum is dioecious, producing male and female flowers are separate plants. Flowers open for short periods of time and males produce pollen in sticky, mucilaginous strands. The research team had noticed that a wonderfully diverse group of aquatic animals visit these flowers during the night and began to wonder if it was possible that at least some of these could be effective pollinators.

Photo by James St. John licensed under CC BY 2.0

The team was up against a bit of a challenge with this idea. A simple visit to a flower doesn't necessarily mean pollination has been achieved. To be an effective pollinator, an animal must a) visit both male and female flowers, b) carry pollen on their bodies, c) effectively transfer that pollen, and d) that pollen transfer must result in fertilization. To quantify all four steps, the team used a series of cameras, aquariums, and natural mesocosm experiments. What they discovered was truly remarkable.

Not only did a diverse array of marine invertebrates visit the flowers during the duration of the study, they also carried pollen, which stuck to their bodies thanks to the thick mucilage. What's more, that pollen was then deposited on the female flowers, which rake up these invertebrates with their tentacle-like stigmas. Finally, pollen deposited on female flowers did in fact result in fertilization. Taken together, these data clearly demonstrate that animal pollinators do in fact exist in aquatic environments. It is likely that these invertebrates are most effective during periods when water movement is minimized. Water currents likely still make up a significant portion of the pollen transfer between individual plants. Still, this evidence changes the paradigm of aquatic pollination in a big way.

Photo Credits: [1] [2]

Further Reading: [1]

Color Changing Asters

Fall is here and the asters are out in force. Their floral displays are some of the last we will see before the first fall frost takes its toll. Their beauty is something of legend and I could sit in a field and stare at them for hours. In doing so, an interesting pattern becomes apparent. Have you ever noticed that the disc flowers of the many aster species gradually turn from yellow to red? Whereas this certainly correlates with age, there must be some sort of evolutionary reason for this.

Indeed, there is. If you sat and watched as bees hurriedly dashed from plant to plant, you may notice that they seem to prefer flowers with yellow discs over those with red. The plot thickens. What about these different colored discs makes them more or less appealing to bees desperately in need of fuel? The answer is pollen.

A closer observation would reveal that yellow disks contain more pollen than those with red discs. Of course, this does relate to age. Flowers with red discs are older and have already had most of their pollen removed. In this way, the color change seems to be signaling that the older flowers are not worth visiting. Certainly the bees notice this. But why go through the trouble of keeping spent flowers? Why not speed up senescence and pour that extra energy into seed production?

Well, its all about cues. Bees being the epitome of search image foragers are more likely to visit plants with larger floral displays. By retaining these old, spent flowers, the asters are maintaining a larger sign post that ensures continued pollinator visitation and thus increases their chances of cross pollination. The bees simply learn over time to ignore the red disc flowers once they have landed. In this way, they maximize their benefit as well.

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

The Cranefly Orchid (Tipularia discolor)

Look closely or you might miss it. Heck, even with close inspection you still run the risk of overlooking it. At this time of year, finding a cranefly orchid (Tipularia discolor) can present a bit of a challenge. At other times of the year the task is a bit easier. If you can find one in bloom, however, you are rewarded with, a unique orchid experience.

For most of the year, the cranefly orchid exists as a single leaf, which is produced in the fall and lasts until spring. It is thought that this orchid takes advantage of the dormancy of its neighbors by sucking up the light the canopy otherwise intercepts during the growing season. Any of you curious enough to look will have noticed that the underside of this leaf is deep purple in color. This very well may be an adaptation to take full advantage of light when it is available. There is some evidence that such coloration may help reflect light back up into the leaf, thus getting more out of what makes it to the forest floor. Evidence for this, however, is limited. It is far more likely that the purple coloration are pigments produced by the leaves that act as a sort of sun screen, shielding the sensitive photosynthetic machinery within from an overdose of sun as intense sun flecks dance across the forest floor.

By the end of spring, the single leaf has senesced. If energy stores were ample that year the plant will then flower. A lanky brown spike erupts from the ground. Its purple-green color is subtle yet beautiful. The flowers themselves are a bit odd, even by orchid standards. Whereas most orchid flowers exhibit satisfying bilateral symmetry, the flowers of the cranefly orchid are distinctly asymmetrical. The dorsal sepal, along with the lateral petals, are scrunched up on either side of the column. This has everything to do with its pollinators.

The cranefly orchid has coopted nocturnal moths in the family Noctuidae for pollination. These moths find the flowers soon after they open and stick around only as long as there is nectar still present in the long nectar spurs. The asymmetry of the bloom causes the pollinia to attach to one of the moth's eyes. In this way the orchid is able to ensure that its pollen is not wasted on the blooms of other species.

As in all plants, the production of flowers is a costly business. Sexual reproduction is all about tradeoffs. It has been found that cranefly orchids that flowered and successfully produced fruit in one year were much less likely to do so in the next. What's more, the overall size of the plant (leaves and corms) were greatly reduced. Its hard to eek out an existence on the forest floor.

What I find most interesting about this species is where it tends to grow. Any old patch of ground simply won't do. Research indicates that the cranefly orchid requires rotting wood as a substrate. It's not so much the wood they require but rather the organisms that are decomposing it. Like all orchids, the cranefly cannot germinate and grow without mycorrhizal associations. They just happen to partner with fungi that also decompose wood. Such a relationship underscores the importance of decaying wood to forest health.

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

On Native Loosestrife and Oil Bees

Oil bees? What the heck are oil bees? Those were my first thoughts when I heard of them for the first time. There are something like 320 species of oil bee in this world, each with their own interesting ecology. These solitary Hymenopterans seek out specific flowers that produce special oils which these bees mix with pollen to feed their developing young. Some even go as far as to use the oils to line their nests. 

Surely these bees must be tropical. I really couldn't imagine this interaction going on up here in the temperate zones. You can imagine my surprise then when I found that there are oil bees and the plants they require haunting some of my favorite hiking spots. As it turns out, some of our native loosestrifes in the genus Lysimachia produce such oils. 

What's more, the bees that utilize them are quite specialized. They all hail from the same genus - Macropis. Female Macropis dig their nests into the ground. Using their highly tuned senses, these solitary bees search far and wide for species of loosestrife that can provide the oils they need. The whorled loosestrife (Lysimachia quadrifolia) is one such species. If you look closely, you can see that the inside of the flowers are streaked with dark resin canals. 

Luckily for the oil bees, this species seems to be quite adaptable as far as habitat goes. I see it most often lining trails and service roads. Mature plants create quite the spectacle with their tall stature, whorled leaves, and sprays of yellow flowers. I will have to pay close attention to these blooms over the next couple of weeks in hopes of seeing the oil bees that share such a close relationship with it. 

Further Reading:
http://bit.ly/28K9k8d

http://bit.ly/28Ks2vV

The Magnificent Mountain Laurel

Mountainsides awash with blooming mountain laurel (Kalmia latifolia) are truly a spectacle. Seeing a sea of pinks, whites, and greens humming with pollinators makes you wonder why such a sight isn't talked about more outside of its range. Why hoards of tourists don't time their seasonal migrations around the blooming of this species is, to me, quite a mystery.

Mountain laurel was a shrub I was quite familiar with growing up. As a child, their shaded tunnel-like understory were some of my favorite places to explore and catch bugs. After moving to New York, I soon forgot about this shrub. Other species became my familiar backdrop. It took visiting the mountains of North Carolina to reawaken these long forgotten memories.

Mountain laurel is generally considered a shrub. In wet, humid areas in the Appalachians, they can readily reach a stature more fitting of a small tree. They are evergreen, holding on to their beautiful leaves throughout the winter. This helps save energy, which is especially useful in poor soils. It also allows mountain laurel to get a head start on photosynthesis as soon as temperatures become favorable.

My favorite part of this shrub are its flowers. Deep pink textured buds soon give way to a floral display that will knock your socks off. Each flower ranges in color from white to pink. Each bloom demands a closer inspection. They are ringed in tiny pockets, each housing an anther. As the flower opens, the pockets hold on to the anthers, drawing them tight. When an insect, especially a bee, disrupts the pockets, the anthers spring out of the pockets and bash the insect with pollen. Each visit is like stumbling into a army of tiny pollen-laden trebuchets. This can easily be simulated using a small stick.

Further Reading:
http://bit.ly/25eAwzI

The Whorled Pogonia

I live for moments like this. The only downside to that is I can never really predict when they are going to happen. There I was driving up a mountain road in search of a handful of other plant species related to my research. The road was narrow and there was a steep bank on the drivers side. The Southern Appalachian Mountains are brimming with botanical diversity. As such, it can be hard to tease out individual plants, especially while driving. This is why having a refined search image comes in handy. 

I was rounding a bend in the road when something out my window caught my eye. My mind went racing and it wasn't long before a suspicion crept into my head. If I was right, this was an opportunity I was not going to miss. I found the nearest pull off, parked the truck, and ran back down the road. I am so happy that I decided to trust my instincts. There in front of me was a small population of whorled pogonia orchids (Isotria verticillata). 

It was like being in the presence of a celebrity that I had been stalking for years. This was an orchid I have been dying to see. The harder I looked the more I saw. I had to sit down. Here in front of me was a species of orchid that isn't seen by many. In fact, entire populations of these species can go unseen for decades until they have enough energy to flower. 

Flowering in this species is said to be quite erratic. Because they live in shaded environments, building up the energy needed to reproduce can be difficult. Like all orchids, the whorled pogonia relies on an obligate relationship with mycorrhizal fungi to supply the nutrients it needs. In return, the orchids provide fungi with carbohydrates. The problem with erratic flowering, however, is that it makes reproduction difficult. Rarely are two populations flowering at the same time and in close enough proximity for successful cross pollination. More often, these orchids will self fertilize, which can lead to high rates of inbreeding. 

Large bees are the main pollinators of the whorled pogonia. The flowers themselves are reported to produce a feint odor reminiscent of Vanilla. This is interesting to note because in the greater scheme of orchid phylogenetics, this species is placed in the Vanilla subfamily, although such distinctions can get muddled quickly. Regardless, simply being in the presence of this orchid was enough to give me goosebumps. It is a shame that such a species is being lost throughout much of its range. 

Further Reading:
http://bit.ly/1ssBmdF

http://bit.ly/1WEmZzm

Three Cheers for Fungus Gnats!

Photo by Canyon Country Discovery Center licensed under CC BY-ND 2.0

Bees, butterflies, bats, and birds... Most of us are all too familiar (and thankful) for their roles as plant pollinators. However, there are some unsung heroes of this niche and one of them are the often overlooked fungus gnats.

Pollinators, for good reason, are one of the largest selective pressures on flower evolution. As flowers evolve to cater to a specific kind of pollinator, be it a bird, a bee, or even fungus gnats, we refer to it as a pollinator syndrome. I have been enchanted by the flowers of the genus Mitella ever since I stumbled across them. As you can see in the picture, they are generally saucer shaped and have snowflake-like appendages protruding from their rim. I wondered, what kind of pollinator syndrome would produce such delicate beauty?

A quick search in the literature turned up a paper from a team of botanists based out of the University of Idaho. The paper outlines work done across a wide range of genera in the Saxifragaceae family. They looked at flower morphology and, through hours of field observation, found a common theme in many species. Those with small, white, saucer-shaped flowers, such as those of Mitella pentandra, all seem to be pollinated by fungus gnats. Fungus gnats are themselves quite small and their larvae live in moist soils, feeding on fungi. As it turns out, the adults are avid pollinators of many plant species and because of this, some species, like M. pentandra, have evolved a pollinator syndrome with them.

The research team also found a strong correlation between fungus gnat flowers and habitat type. They all seemed to be tied to moist forest habitats. This is because moist forests are the only place fungus gnats can live. Plants in drier habitats rarely come into contact with fungus gnats and therefore have no selective pressures to cater to these insects.

I love it when general observations based on aesthetics lead to a deeper understanding of what is going on outside.

Photo Credit: Four Corners School of Outdoor Education (http://bit.ly/1jmNLDR)

Further Reading:
http://bit.ly/1VFiHY4

Throwing it to the Wind

Though many of you may be cursing this fact, in the temperate regions of the north, wind pollinated trees are bursting into bloom. Their flowers aren't very showy. They don't have to be. Instead of relying on other organisms for pollination, these trees throw it to the wind, literally.

It is an interesting observation to note that the instances of wind pollinated tree species increases with latitude and elevation. This makes a lot of sense. It is most effective in open areas where wind is at its strongest. That is why many wind-pollinated trees get down to business before they leaf out.

The fewer obstructions the better. Also, pollinators can be hard to come by both at high elevation and high latitudes. Therefore, why not let the wind do all the work? This is also why wind-pollination is most common in early succession and large canopy species. Similarly, this is also why you rarely encounter wind-pollinated trees in the tropics. Leaves are out year round and pollinators are in abundance.

Without pollinators, wind-pollinated trees don't need to invest in showy flowers. That is why they often go unnoticed by folks. Instead, they pour their energy into pollen production. Your irritated sinuses are a vivid reminder of that fact. Wind pollination is risky. It relies mostly on chance. Therefore, the more pollen a tree pumps out, the more likely it will bump into a female. However, some trees like red maples (Acer rubrum) combine tactics, relying on both wind and hardy spring pollinators for their reproduction.

Whether you love this time of year or dread it, it is nonetheless interesting to see how static organisms like trees cope with the difficulties of sexual reproduction. I enjoy sitting in my yard and watching pines billow pollen like smoke from a fire. If anything, it is a stark reminder of how important sexual reproduction is to the myriad organisms on this planet.

Further Reading:
http://bit.ly/1qnRUm2

Spathiphyllum - A Natural Perspective on a Common Houseplant

http://bit.ly/1PjmVkrhttp://bit.ly/1PjmVkrI will never take peace lilies for granted again. As many of you reading this can empathize, I have up until this point only encountered these plants as sad looking additions to a dark corner of the home or office. Their ease of care has earned them the honor of living among even the least botanically inclined. Though we call them peace lilies, these plants are not lilies at all. They actually belong to the family Araceae, which makes them distant relatives of plants like Jack-in-the-pulpit.

All peace lilies belong in the genus Spathiphyllum. There are something like 40 different species that grow in tropical regions of Central and South America as well as southeastern Asia. As horticultural specimens, they aren't difficult. Modest light and the occasional watering are about all these plants need. Like all house plants though, I have wondered about how these plants behave in the wild.

During a trip to Costa Rica, I was very fortunate to observe some interesting behavior. Wild growing Spathiphyllum inflorescences have a scent. You would never know this based on the plants you find for sale at the local nursery. Like many roses, it would seem the their natural floral scent has largely been bred out of captive individuals. This scent is obviously meant to attract pollinators, however, the type of pollinators being targeted came as quite a surprise.

As I looked over a large patch of flowering Spathiphyllum, I was flabbergasted when I realized just what was visiting the spadix - Euglossine bees! Euglossine bees are collectively referred to as orchid bees (http://bit.ly/1hUaChe). This is because the males require specific scent compounds to attract females. They do not produce these compounds naturally. Instead, they must collect them from the flowers of orchids such as Stanhopea, Gongora, and Catasetum.

Well, as it turns out, orchid bees also collect scent from the spadix of Spathiphyllum blooms! The whole while I was watching this group of plants, multiple Euglossine bees paid a visit. What was most exciting is that many of the bees had orchid pollinia stuck to their backs. This was evolutionary ecology in progress and I was witnessing it first hand!

Its a real shame that we have altered captive Spathiphyllum in such a way that they do not produce scent. The smell is heavenly to say the least.

Further Reading:

American Witch Hazel

With October nearly over, temperatures are starting to dip. The asters and goldenrods have traded their floral displays for their wind-dispersed seeds that take advantage of the fall breeze. Alas, floral displays in the northern hemisphere are nearly over. There is one major show left for those living in eastern North America. From October through November (and even into December in some regions) one species of understory shrub puts forth a display reminiscent of a firework extravaganza if the fireworks only came in yellow.

I am, of course, talking about American witch hazel (Hamamelis virginiana). This wonderful shade-loving shrub goes largely unnoticed throughout the summer. Come fall, however, it makes up for its subtle appearance by offering up some of the last flowers of the season. Seemingly overnight their branches become adorned with unique little flowers whose petals shoot out like four little party streamers. They somehow manage to look both modest and showy all at once.

It may seem strange for any plant to be flowering so late. What possible advantage could this entail? Some experts believe that late flowering evolved as a way for American witch hazel to avoid competition with other flowering plants. Indeed, it certainly attracts its fair share of pollinators in desperate search of a late season meal. Flies and bees make up a majority of pollinator visits. It could also be possible that American witch hazel flowers so late to avoid hybridizing with its spring-flowering cousin, the Ozark witch hazel (Hamamelis vernalis). Regardless of its "intentions," this fall flowering strategy comes at a cost.

Despite garnishing a fair amount of pollinator attention, American witch hazel doesn't have enough time following pollination to produce fruit before winter hits. As such, fertilization of the ovaries is delayed until May the following year. The fruits, which are contained in woody capsules, spend the entire growing season maturing into viable propagules. Once mature, the seed capsules begin to dry until they become so taught that the capsule bursts. If you are lucky and attentive enough, you may be able to hear a small snap as the seeds are forcibly ejected from the capsule.

What's more, fruit set in this species is rather low. Analyses of over 40,000 witch hazel flowers showed that less than 1% produced viable seeds. Despite all of this, American witch hazel is nonetheless a successful species in eastern North American forests. It is proof that evolution need not be all or nothing. Any slight advantage is still an advantage. This hardy shrub is, at the end of the day, a survivor.

Further Reading:
http://www.amjbot.org/content/89/1/67.abstract

Mighty Mighty Squash Bees

Photo by MJI Photos (Mary J. I.) licensed under CC BY-NC-ND 2.0

It's decorative gourd season, ladies and gentlemen. If you are anything like me then you should be reveling in the tastes, smells, and overall pleasing aesthetics of the fruit of the family Cucurbitaceae. If so, then you must pay your respects to a hard working bee that is responsible for the sexual efforts of these vining plants. I'm not talking about the honeybee, no no. I am talking about the squash bees. 

If we're being technical, the squash bees are comprised of two genera, Peponapis and Xenoglossa. They are not the hive forming bees we generally think of. Instead, these bees are solitary in nature. After mating (which usually occurs inside squash flowers) the females will dig a tunnel into the ground. Inside that tunnel she places balls of squash pollen upon which she will lay an egg. The larvae consume the protein-rich pollen as they develop. 

The story of squash bees and Cucurbitaceae is a North American story. Long before squash was domesticated, these bees were busy pollinating their wild relatives. As a result, this bee/plant relationship is quite strong. Female squash bees absolutely rely on squash flowers for the pollen and nectar needs of their offspring. In fact, they often dig their brood tunnels directly beneath the plants. 

Because of this long standing evolutionary relationship, squash bees are the best pollinators of this plant family. The flowers open in the morning just as the squash bees are at their most active. Also, because they are so specific to squash, the squash bees ensure that pollen from one squash flower will make it to another squash flower instead of an unrelated plant species. Honeybees can't hold a candle to these native bees. What's more, crowds of eager honeybees may even chase off the solitary squash bees. For these reasons, it is often recommended that squash farmers forgo purchasing honeybee hives for their crops. If left up to nature, the squash bees will do what they are evolutionarily made to do. 

Photo Credit: MJI Photos (https://www.flickr.com/photos/capturingwonder/4962652272/)

Further Reading:
http://www.researchgate.net/profile/Victor_Parra-Tabla2/publication/226134213_Importance_of_Conserving_Alternative_Pollinators_Assessing_the_Pollination_Efficiency_of_the_Squash_Bee_Peponapis_limitaris_in_Cucurbita_moschata_(Cucurbitaceae)/links/549471010cf20f487d2a95b8.pdf

http://www.jstor.org/stable/25084168?seq=1#page_scan_tab_contents

http://extension.psu.edu/plants/sustainable/news/2011/jan-2011/1-squash-bees

Vanilla Is Anything But Vanilla

Photo by H. Zell licensed under CC BY-SA 3.0

Vanilla companies seem to be lacking in their plant ID skills. You so rarely see any vanilla products with the correct flower on the label. While I can't speak for everyone, I think I may have a hunch as to why most companies slap a white Phalaenopsis, Dendrobium, or any of the other orchid flowers that could remotely pass for being Vanilla on their products. At the same time, it also explains the rather pricey nature of Vanilla "beans."

The answer, I believe, lies in the flowers themselves. Vanilla is a genus of orchids that contains roughly 110 species that span the tropical regions of the globe. They are vining orchids, climbing trunks of trees in an attempt to make their bid for the canopy. Some Vanilla orchids have lost their leaves entirely, relying solely on their green, photosynthetic stems and roots. The species that gives us the highly coveted vanilla flavor is Vanilla planifolia from Central America.
 

Photo by Dinesh Valke licensed under CC BY-SA 2.0

Vanilla planifolia, like most other species of Vanilla, produce very short-lived, non-selfing flowers. They open up as the sun begins to rise and are mostly closed by afternoon. Vanilla are not self-fertile so if the flower has not been fertilized by afternoon, it will simply wither and fall off. Because of their ephemeral nature, it is probably hard for most vanilla companies to do the kind of photo shoot they would need to do their marketing. It is likely that they just fall back on orchids that kind of look like Vanilla and I am sure that outside of us botanical enthusiasts, no one really faults them for it.

The Vanilla reproductive strategy also lends to the pricey nature of real Vanilla "beans." In the wild, Vanilla relies on stingless bees for pollination. In most cases, Vanilla growers do not rely on the bees because, if they are present, fertilization rates are often extremely low. And, if the bees are not present, the plants will not reproduce on their own. Because of this, Vanilla growers must hand pollinate all of the flowers individually.

This is a labor intensive process that must be done at just the right time if it is to work. The resulting "bean" is not a bean at all but rather a large capsule filled with millions of dust-like seeds. The capsules themselves require about 6 weeks to fully mature and then sometimes as long as 9 months to properly cure and produce their characteristic vanilla flavor. So yes, I think it is safe to say that Vanilla is anything but vanilla.

Photo Credit: [1] [2]

Further Reading: [1]

Groundnut

As common names go, groundnut doesn't quite seem fitting for such a distinctive plant. Known scientifically as Apios americana, this leguminous vine can be found growing along a variety of edge habitats throughout much of eastern North America. It becomes most obvious to passers by from July through September when it is flowering. 

Okay, to be fair, groundnut is a fairly accurate description. Not only are the seeds of this vine edible, so too are the starchy tubers it grows from. However, I think this all detracts from a rather intriguing ecology. Populations of groundnut occur in one of two forms - diploid (2 sets of chromosomes) or triploid (three sets of chromosomes). It would seem that entire populations can sometimes consist of the triploid variety. 

This is a bit odd because triploid plants are sterile. Though they produce seemingly functional flowers, they never produce seed. Instead, these populations reproduce vegetatively via their underground tubers. Other than their lack of reproductive ability, there doesn't seem to be any other noticeable differences between diploids and triploids. Whatever the reason, it is obviously working for the groundnut.

Via Internet Archive Book Images under Public Domain

Speaking of reproduction, there seems to be a bit of mystery concerning the types of pollinators targeted by this vine. Groundnut flowers, with their carrion-like appearance and strange odor, may be attracting carrion flies. Some authors are rather set on this hypothesis despite very little evidence. A more thorough investigation into the pollination ecology of groundnut revealed that bees were the only visitors, however, nothing conclusive could be said about their effectiveness.

What can be said is that the flowers require insects of a certain size for pollination to occur. The flowers themselves are essentially miniature spring traps. When insects of a certain size land on the flowers they trigger the release of the anthers, which slam into the insect, dusting it with pollen. This is a very similar strategy to a close relative of groundnut, alfalfa (Medicago sativa), which is definitely bee pollinated. 

Despite all of the confusion surrounding groundnut, it is nonetheless a great species. It fixes nitrogen, provides food for wildlife and humans alike, and looks really cool to boot. This would be a great addition to a native plant garden throughout its range. 

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

Pollination Plasticity

© Danny Keßler

Pollinators are great -- that is, unless they also feed upon the plant they are pollinating. In the arid regions of western North America, Nicotiana attenuata, sometimes referred to as coyote tobacco, has this very problem. 

Blooming at night, its white flowers are heavily scented, which attracts its pollinator, a species of hawkmoth known to science as Manduca quinquemaculata. Female hawkmoths do a little bit more than just grab a sip of nectar. Their larvae feed on members of the tobacco family and, as anyone with tomatoes can tell you, they have a voracious apatite. Visiting female moths use the meal break as a chance to lay their eggs. However, this does not have to be a death sentence for the plant. Researchers noticed a strange thing about N. attenuata plants that had feeding damage from hawkmoth caterpillars. Their flowers seemed to change.

Photo by Stan Shebs licensed under CC BY-SA 3.0

And change they did. Coyote tobacco plants with caterpillars will start to produce flowers that open during the day, instead of at night. The plants also stopped producing a scent. What's more, the flowers didn't open very far either. What is the reason for these drastic changes? Are the plants stressed out from the caterpillar attack?

Not exactly. In fact, the answer is quite remarkable. As it it turns out, plants with caterpillars munching on them were intentionally shifting their entire reproductive strategy to avoid the larvae of their intended pollinators. Flowers that open during the day no longer attracted the attention of moths, which reduced the number of new eggs being laid. Instead, the flowers started attracting the attention of hummingbirds. Hummingbirds are pretty effective as pollinators and their offspring don't eat the plants that their parents feed on. 

Manduca quinquemaculata adult male. Photo by Didier Descouens licensed under CC BY-SA 4.0

So, how does the plant know when its being fed upon? Caterpillar spit. Chemicals in the saliva of the caterpillar trigger a chemical response within the plant that tells it to start ramping up defenses (of which nicotine is one). This signaling cascade also tells the plant to start producing day opening flowers instead of night opening flowers. It just goes to show you how a little attention to detail can uncover some amazing aspects of the world around us. 

Photo Credit: Danny Kessler, MPI chemische Ökologie, Wikimedia Commons

Further Reading: [1] [2]

Flower Color Beyond What We Can See

Photo by Plantsurfer licensed under CC BY-SA 3.0

Despite their aesthetic appeal, flowers are not here to dazzle us. While they have enticed us to spread the offspring of many species around the globe, flowers have one purpose and one purpose only - sex. 

There are many different and even tricky ways flowers manage pollination. The most common and by far the most widely utilized is the use of insects. Though flowers look like they have done everything they can to attract pollinators, we can only see a narrow range of the electromagnetic spectrum. What we see as visible light is only a mere fraction of what is really out there. 

Many insects see well into the ultraviolet range and this has caused some very interesting evolutionary adaptations in flowers to attract insects to their business parts. When viewed with UV cameras, many species of plants have seemed to have drawn maps and arrows to their anthers and stigmas. It is amazing to witness a species of say Potentilla with, to us, solid yellow petals in this manner. The patterns that appear are striking! There are far too many examples to go into detail on this subject so instead, here is a great website to show you some examples 

http://www.naturfotograf.com/UV_flowers_list.html

Invasive Ants Destroy Plant Sex Lives

Photo by Lalithamba licensed under CC BY 2.0

For all of the amazing symbioses ants and plants share, there is one thing ants seem to get in the way of... plant sex. That's right, plants have found a use for ants in pretty much every way except for when it comes to reproduction (with some exceptions of course). Ants being what they are, they can easily become a force to be reckoned with. For this reason, many plant species have co-opted ants as defense agents, luring them in with nectar-releasing glands, a resource that ants guard quite heavily. 

When it comes to flowering, however, ants can become a bit overbearing. Research done at the University of Toronto shows that the invasive European fire ant has a tendency to guard floral nectar so heavily that they chase away pollinators. By observing fire ants and bumblebees, they found that ants change bumblebee foraging behaviors. The fire ants often harassed and attacked bumblebees as they visited flowers, causing them to spend significantly less time at each flower, a fact that could very well result in reduced pollination for the plant in question. 

This reduction in pollination is made even more apparent for dioecious plants. Since ants are after nectar and not pollen, male flowers received more bumblebee visits than nectar-producing female flowers. This could become quite damaging in regions with heavy fire ant infestations. 

As it turns out, the ants don't even need to be present to ward off bumblebees. The mere scent of ants was enough to cause bumblebees to avoid flowers. They apparently associated the ant smell with being harassed and are more likely to not chance a visit. Of course, this study was performed on using an invasive ant species. Because so many plant species recruit ants for things like protection and seed dispersal, it is likely that under natural conditions, the benefit of associating with ants far outweighs any costs to reproductive fitness. More work is needed to see if other ant specie exhibit such aggressive behavior towards pollinators. 

Photo Credit: Lalithamba (https://www.flickr.com/people/45835639@N04)

Further Reading:

 http://www.researchgate.net/profile/James_Thomson13/publication/259319739_Ants_and_Ant_Scent_Reduce_Bumblebee_Pollination_of_Artificial_Flowers/links/554b8fd90cf21ed213595eff.pdf

Mayapple

All across eastern North America, one of my all time favorite wildflowers is coming into bloom. Looking like some sort of strange, tropical umbrella, mayapple (Podophyllum peltatum) is more easily recognizable by its overall appearance than its flowers. However, bend down and take a look under any plant with two leaves and you will be rewarded by one heck of a bloom. 

At home in the family Berberidaceae, the genus Podophyllum is predominantly Asian. Mayapple is the only species within this genus found anywhere else in the world. Mayapples exhibit two forms of reproduction, rhizomatous and sexual. When you see a great big stand of mayapple in the forest, there is a good chance they are all genetically identical. The rhizomes spread out underground, throwing up new plants as they go. This method of asexual reproduction has interesting implications for how this plant reproduces sexually. 

Mayapples will not self-pollinate. They need to cross with a genetically different individual for proper seed set. This can be troublesome in that mayapple flowers do not produce nectar and bees quickly become savvy to this and are less likely to visit multiple different patches of flowering mayapples consecutively. This is where neighboring flowers come into play. Research has shown that mayapples patches growing near flowering plants that do offer rewards to pollinators are significantly more likely to be pollinated themselves. Apparently bees aren’t as dissuaded by mayapples ruse when there are plenty of other meals to be had.

For mayapples, flowering brings with it an additional set of challenges. It takes a lot of energy to produce flowers, fruits, and seeds. Research has also demonstrated that flowering and fruit production in mayapples significantly decreases the chances of flowering in the future and significantly increases the likelihood of the plants demise. Still, enough plants survive long enough to flower multiple times throughout their life. 

Photo by Nicholas A. Tonelli licensed under CC BY 2.0

Mayapples, as the common name suggests, produce rather large fruit that turns a bright yellow when ripe. This is the only time in which consuming a piece of mayapple is safe as this species is highly toxic. This does not seem to deter other animals though. In my experience, fruits are short lived on the plant, quickly being gobbled up by raccoons and the like. The most interesting aspect of mayapple ecology to me is that, in at least part of its range, mayapple relies on box turtles as their main seed dispersers. Box turtles relish the fruit and seeds passing through the gut of the turtle are much more likely to germinate. All in all this is a familiar friend that never disappoints. If you are lucky enough to live where mayapples are native, get outside and experience a mayapple bloom for yourself. You will be very glad that you did!

Photo Credits: [2] [3]

Further Reading: [1] [2] [3] [4] [5]

The Arisaema Complex

If you live in the east, Jack-in-the-pulpit or Arisaema triphyllum, is most likely an unmistakable part of late spring. Being a member of the arum family, the bracts of the plant form a tube and hood over the spadix and flowers. This is a highly variable species, in fact, there are at least 4 recognized subspecies that make up the Arisaema complex, A. triphyllum ssp. pusillum, A. triphyllum ssp. quinatum, A. triphyllum ssp. stewardsonii, and A. triphyllum ssp. triphyllum.

Interestingly enough, each subspecies seems to be reproductively isolated from the others. Each also seems to prefer its own habitat. For instance, triphyllum, a denizen of rich woods, blooms after the last frosts while stewardsonii, a denizen of swamps and bogs, blooms a few weeks later. Another interesting aspect of this complex is that pusillum and stweardsonii are both diploid plants, having 28 sets of chromosomes each, whereas triphyllum, our most common subspecies, is believed to be a hybrid of the two and is tetraploid and thus has 56 sets of chromosomes. Some would argue that these plants should be treated as distinct species since the characteristics that designate each subspecies seem rather specific but all across their range, there are many plants that seem to blur the lines. This is a debate that is only going to be solved by more accurate DNA analysis. However, nature doesn't seem to be reading any science texts and therefore rarely falls into our neat, clear-cut mindsets.

Being an arum, this species does produce some heat as well as an odor. The flowers produce a smell reminiscent of mushrooms and indeed, this is to attract their main pollinators, fungus gnats. Next time you come across a blooming Jack-in-the-pulpit, get down and take a whiff. It isn't necessarily good or bad but either way it is an experience. This species is gaining some traction in the gardening community as well due to its ease of care and unique appearance. It is also easy to establish from seed, however, make sure to wear gloves and avoid any skin contact while de-fleshing the seeds because being that it is a member of the arum family, this species produces calcium oxalate crystals that can cause severe burning.

Further Reading:
http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=222000013

http://www.theprimrosepath.com/Featured_Plants/Arisaema_triphyllum/triphyllumcomplex.htm

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

http://www.amjbot.org/content/90/12/1729.full.pdf+html?sid=5babeddb-908d-4782-a866-6e0938b93580

http://www.amjbot.org/content/91/6/881.full.pdf+html?sid=5babeddb-908d-4782-a866-6e0938b93580

Colorful Claytonia

If you live where spring beauty, specifically Claytonia virginica, is native, then you may have noticed great variations in flower color. We all know the influence pollinators can have on flower shape and color but how do we explain populations with such a spectrum?

Like me you might be thinking that it is related to its growing conditions. Well, researched based out of Indiana University would suggest otherwise. It turns out, the variety of flower color in Claytonia has to do with opposing natural selection from herbivores and pathogens.

In a 2 year study, researchers made some amazing discoveries about how herbivores, pollinators, and pathogens can interact to produce the variety of flower colors one can find in any given Claytonia population. First, they made sure that Claytonia flower color is not a result of soil pH or anything like that by growing a ton of them in different conditions. They were able to demonstrate that flower color is indeed genetic and is controlled by a couple different compounds. Crimson coloring comes from a compound called "cyanidin" and white colors comes from two flavonols, "guercetin" and "kaempferol". Researchers then used spectrometry to analyze flower colors throughout the population and found 4 distinct color morphs ranging from all white to mostly crimson.

As it turns out, the flavonol compounds have pleiotropic effects in Claytonia. While they do produce white pigments, they also help defend the plants against herbivory and pathogens. Researchers then used a multitude of different analytical methods to assess overall fitness of each color morph and the results are jaw-droppingly cool to say the least.

Fitness of Claytonia was measured as total fruit production and total seed set. Because Claytonia needs a pollinator to visit the plant in order to produce fruit and set seed, reproduction is directly linked to pollinator preference. This research showed that pollinators, which for Claytonia are solitary bees, do, in fact, prefer crimson color morphs. This helps to explain the greater number of crimson colored flowers in in many populations because the more pollinators that visit a flower, the higher overall fitness for that plant. What it does not explain though, is why white morphs exist in the population at all.

As stated above, the flavonols that produce white pigmentation also beef up the plants defenses. It was found that white colored flowers experienced significantly less predation than crimson flowers. This is big news because herbivory has serious consequences for Claytonia. Plants that receive high levels of herbivore damage are far more likely to die. Because of this, white morphs, even with significantly less reproductive fitness, are able to maintain themselves in any given population.

If you're at all like me then you may need to pick you jaw up off the ground at this point. But wait! It gets cooler.... In areas where other white flowering plants like Stellaria pubera abound, white Claytonia morphs are even more rare. Why is this exactly? Well, this is due to a push towards a more pollinator-mediated selective pressure. In areas where many plants share the same flower color, it pays to be different. This causes a selective pressure in these Claytonia populations to favor even more crimson color morphs.

Isn't evolution amazing?

Further Reading:

http://bit.ly/1QxVy5Q

http://plants.usda.gov/java/profile?symbol=clvi3