Your string of pearls (and its cousins) are all members of the daisy family

Photo by LynnK827 licensed by CC BY-NC-ND 2.0

I love the spike in popularity of houseplants. The more popular indoor gardening becomes, the more plants become available for obsessive growers such as myself. If you are like me, then learning about the ecological and evolutionary history of the plants you keep makes them all the more special. Take, for instance, a small group of scrambling succulents affectionately referred to as “string of pearls,” “string of bananas,” and “string of tears.” These all make incredible houseplants if given the proper care, but they become all the more interesting when you realize that they are distant cousins of the dandelions growing in your yard.

That’s right, each of these species are highly derived members of the daisy family (Asteraceae). Their taxonomy has been a bit wonky over the years. When I first took interest in these succulents, they resided in the genus Senecio. Some authors have suggested moving them into the genus Kleinia or Cacalia, but current systematics suggests they belong in a genus of their own - Curio. Inspection of the relationships within this group reveals that closely related species have evolved slightly different growing habits. The plants I will be focusing on for this article each resemble creeping vines but many of their close relatives are less vine-like but nonetheless still creep along the ground. For the sake of this piece, I am going to stick with the genus Senecio because, regardless of their taxonomic placement, the “sting of” clade is super fascinating from an ecological standpoint.

Senecio citriformis photo by Salchuiwt licensed by CC BY-SA 2.0

Senecio radicans photo by KENPEI licensed by CC BY-SA 3.0

All of these stringy plants hail from arid regions of South Africa. In the wild, they mostly scramble over rocks and bushes, often emerging out of cracks in rock in search of the right microclimate. Their oddly shaped, succulent leaves are an evolutionary adaptation to the tough conditions in which they evolved. The most leaf-like anatomy belongs to that of the string of bananas (S. radicans). Each leaf of S. radicans is shaped like a tiny green banana. More extreme versions of leaf morphology are found in the string of tears (S. citriformis) and string of pearls (S. rowleyanus & S. herreianus). The leaves of these three species resemble peas in shape, size and color. The leaves of S. rowleyanus are more spherical in shape (pearls), whereas the leaves of S. citriformis taper towards the tip (tears).

Senecio herreianus photo by Frank Vincentz licensed by CC BY-SA 3.0

Though all of these species grow in dry habitats, the more spherical shaped leaves of S. rowleyanus and S. citriformis are thought to be best adapted for drought. In growing spherical leaves, these plants are taking advantage of the surface area to volume ratio of a sphere. The benefit of this is that these species are able to maximize water storage while minimizing the amount of leaf surface exposed to the blistering sun. This way the leaves are able to maintain high levels of photosynthesis without overheating, all the while reducing leaf temperature.

In each of these species, the surface or adaxial side of the leaf exhibits a translucent window that runs the length of the leaf. It has long been hypothesized that leaf windows allow light to transmit into deep into the interior of the leaf where the photosynthetic machinery resides. More recent experiments on window-leaved succulents suggests that reality is not that simple. Instead, these windowed surfaces appear to allow the plant to maintain healthy levels of photosynthesis without the damaging their leaves via overheating.

Photo by Frank Vincentz licensed by CC BY-SA 3.0

When plants reach maturity, flowering can be prolific. Thin stems topped with tiny composite heads of cream-colored flowers erupt from the mat of vegetation. Then and only then do these plants readily reveal their placement within the daisy family. The inflorescence is made up entirely of discoid flowers. There are no rays like that of a sunflower. The flowers themselves are said to produce a pleasant odor frequently described as sweet and spicy. After pollination, the flowers give way to seeds topped with a parachute-like pappus that will carry them far and wide on the wind.

Learning about the natural history of these plants has given me a whole new appreciation of these strange, succulent members of the daisy family. What’s more, there is a whole world of succulent asters out there (a post for a later time) and many of them are equally as fascinating and beautiful.

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

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

Getting to Know Sansevieria

Photo by Mokkie licensed under CC BY-SA 3.0

The houseplant hobby is experiencing something of a renaissance as of late. With their popularity on various social media platforms, easy to grow plant species and their cultivars are experiencing a level of popularity they haven't seen in decades. One genus of particular interest to houseplant hobbyists is Sansevieria.

Despite their popularity, the few Sansevieria species regularly found in cultivation come attached with less than appealing common names. Mother-in-law's tongue, Devil's tongue, and snake plant all carry with them an air of negativity for what are essentially some of the most forgiving houseplants on the market. What few houseplant growers realize is that those dense clumps of upright striped leaves tucked into a dark corner of their home belong to a fascinating genus worthy of our admiration. What follows is a brief introduction to these enigmatic houseplants.

Sansevieria cylindrica. Photo by Marlon Machado licensed under CC BY-NC 2.0

Sansevieria ballyi. Photo by jurosig licensed under CC BY-NC-SA 2.0

The Sansevieria we encounter in most nurseries are just the tip of the iceberg. Sansevieria is a genus comprised of about 70 different species. I say 'about' because this group is a taxonomic mess. There are a couple reasons for this. For starters, the vast majority of Sansevieria species are painfully slow growers. It can take decades for an individual to reach maturity. As such, they have never really presented nursery owners with much in the way of economic gain and thus only a few have received any commercial attention.

Another reason has to do with the fiber market during and after World War II. In hopes of discovering new plant-based fibers for rope and netting, the USDA collected many Sansevieria but never formally described most of them. Instead, plants were assigned numbers in hopes that future botanists would take the time needed to parse them out properly.

A third reason has to do with the variety of forms and colors these plants can take. Horticulturists have been fond of giving plants their own special cultivar names. This complicates matters as it is hard to say which names apply to which species. Often the same species can have different names depending on who popularized it and when.

Sansevieria grandis in situ. Photo by Ton Rulkens licensed under CC BY-SA 2.0

Regardless of what we call them, all Sansevieria hail from arid regions of Africa, Madagascar and southern Asia. In the wild, many species resemble agave or yucca and, indeed, they occupy similar niches to these New World groups. Like so many other plants of arid regions, Sansevieria evolved CAM photosynthesis as a means of coping with heat and drought. Instead of opening up their stomata during the day when high temperatures would cause them to lose precious water, they open them at night and store CO2 in the form of an organic acid. When the sun rises the next day, the plants close up their stomata and utilize the acid-stored carbon for their photosynthetic needs.

The wonderfully compact Sansevieria pinguicula. Photo by Peter A. Mansfeld licensed under CC BY 3.0

Often you will encounter clumps of Sansevieria growing under the dappled shade of a larger tree or shrub. Some even make it into forest habitats. Most if not all species are long lived plants, living multiple decades under the right conditions. These are just some of the reasons that they make such hardy houseplants.

The various Sansevieria appear to sort themselves out along a handful of different growth forms. The most familiar to your average houseplant enthusiast is the form typified by Sansevieria trifasciata. These plants produce long, narrow, sword shaped leaves that point directly towards the sky. Many other Sansevieria species, such as S. subspicata and S. ballyi, take on a more rosetted form with leaves that span the gamut from thin to extremely succulent. Still others, like S. grandis and S. forskaalii, produce much larger, flattened leaves that grow in a form reminiscent of a leaky vase. 

Sansevieria trifasciata with berries. Photo by Mokkie licensed under CC BY-SA 3.0

Regardless of their growth form, a majority of Sansevieria species undergo radical transformations as they age. Because of this, adults and juveniles can look markedly different from one another, a fact that I suspect lends to some of the taxonomic confusion mentioned earlier. A species that illustrates this nicely is S. fischeri. When young, S. fischeri consists of tight rosettes of thick, mottled leaves. For years these plants continue to grow like this, reaching surprisingly large sizes. Then the plants hit maturity. At that point, the plant switches from its rosette form to producing single leaves that protrude straight out of the ground and can reach heights of several feet! Because the rosettes eventually rot away, there is often no sign of the plants previous form.

A mature Sansevieria fischeri with its large, upright, cylindrical leaves. Photo by Peter A. Mansfeld licensed under CC BY 3.0

If patient, many of the Sansevieria will reach enormous sizes. Such sizes are rarely observed as slow growth rates and poor housing conditions hamper their performance. It's probably okay too, considering the fact that, when fully grown, such specimens would be extremely difficult to manage in a home. If you are lucky, however, your plants may flower. And flower they do!

Though there is variation among the various species, Sansevieria all form flowers on either a simple or branched raceme. Flowers range in color from greenish white to nearly brown and all produce a copious amount of nectar. I have even noticed sickeningly sweet odors emanating from the flowers of some captive specimens. After pollination, flowers give way to brightly colored berries, hinting at their place in the family Asparagaceae.

A flowering Sansevieria hallii. Photo by Ton Rulkens licensed under CC BY-SA 2.0

As a whole, Sansevieria can be seen as exceptional tolerators, eking out an existence wherever the right microclimate presents itself in an otherwise harsh landscape. Their extreme water efficiency, tolerance of shade, and long lived habit has lent to the global popularity of only a few species. For the majority of the 70 or so species in this genus, their painfully slow growth rates means that they have never made quite a splash in the horticulture trade.

Nonetheless, Sansevieria is one genus that even the non-botanically minded among us can pick out of a lineup. Their popularity as houseplants may wax and wane but plants like S. trifasciata are here to stay. My hope is that all of these folks collecting houseplants right now will want to learn more about the plants they bring into their homes. They are more than just fancy decorations, they are living things, each with their own story to tell. 

NOTE: Since writing this article, I have learned that the genus Sansevieria has been lumped into the genus Dracaena. For the sake of familiarity, I retain the generic name Sansevieria for this article.

Photo Credits: [1] [2] [3] [4] [5] [6] [7] [8]

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

The Plight of the African Violets

Photo by RobertoMM licensed under CC BY-SA 3.0

For many of us, African violets (Saintpaulia spp.) are some of the first houseplants we learned how to grow. They are not true violets (Violaceae), of course, but rather members of the family Gesneriaceae. Nonetheless, their compact rosettes of fuzzy leaves coupled with regular sprays of colorful flowers has made them a multi-million dollar staple of the horticultural industry. Unfortunately their numbers in captivity overshadow a bleak future for this genus in the wild. Many African violets are teetering on the brink of extinction.

The genus Saintpaulia is endemic to a small portion of east Africa, with a majority of species being found growing at various elevations throughout the Eastern Arc Mountains of Kenya and Tanzania. Most of the plants we grow at home are clones and hybrids of two species, S. ionantha and S. confusa. Collected in 1892, these two species were originally thought to be the same species, S. ionantha, until a prominent horticulturist noted that there are distinct differences in the seed capsules each produced. Since the 1890's, more species have been discovered.

Saintpaulia goetzeana

Exactly how many species comprise this genus is still up for some debate. Numbers range from as many as 20 to as few as 6. Much of the early work on describing various Saintpaulia species involved detailed descriptions of the density and direction of hairs on the leaves. More recent genetic work considers some of these early delineations to be tenuous at best, however, even these modern techniques have resolved surprisingly little when it comes to a species concept within this group.

Saintpaulia sp. in situ. Photo by TanzaniaPlantCollaboration licensed under CC BY-NC-SA 2.0

Though it can be risky to try and make generalizations about an entire genus, there are some commonalities when it comes to the habitats these plants prefer. Saintpaulia grow at a variety of elevations but most can be found growing on rocky outcrops. Most of them prefer growing in the shaded forest understory, hence they do so well in our (often) poorly lit homes. Their affinity for growing on rocks means that many species are most at home growing on rocks and cliffs near streams and waterfalls. The distribution of most Saintpaulia species is quite limited, with most only known from a small region of forest or even a single mountain. Its their limited geographic distribution that is cause for concern.

Saintpaulia ionantha subsp. grotei in situ.

Regardless of how many species there are, one fact is certain - many Saintpaulia risk extinction if nothing is done to save them. Again, populations of Saintpaulia species are often extremely isolated. Though more recent surveys have revealed that a handful of lowland species are more widespread than previously thought, mid to highland species are nonetheless quite restricted in their distribution. Habitat loss is the #1 threat facing Saintpaulia. Logging, both legal and illegal, and farming are causing the diverse tropical forests of eastern Africa to shrink more and more each year. As these forests disappear, so do Saintpaulia and all of the other organisms that call them home.

There is hope to be had though. The governments of Kenya and Tanzania have recognized that too much is being lost as their forests disappear. Stronger regulations on logging and farming have been put into place, however, enforcement continues to be an issue. Luckily for some Saintpaulia species, the type localities from which they were described are now located within protected areas. Protection coupled with inaccessibility may be exactly what some of these species need to survive. Also, thanks to the ease in which Saintpaulia are grown, ex situ conservation is proving to be a viable and valuable option for conserving at least some of the genetic legacy of this genus.

Saintpaulia intermedia [source]

It is so ironic to me that these plants can be so common in our homes and offices and yet so rare in the wild. Despite their popularity, few recognize the plight of this genus. My hope is that, in reading this, many of you will think about what you can do to protect the legacy of plants like these and so many others. Our planet and the species that call it home are doomed without habitat in which to live and reproduce. This is why land conservation is an absolute must. Consider donating to a land conservation organization today. Here are two worth your consideration:

The Nature Conservancy

The Rainforest Trust

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

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

Apocynaceae Ant House

Bullate leaves help the vine clasp to the tree as well as house ant colonies. Photo by Richard Parker licensed under CC BY-NC-SA 2.0

The dogbane family, Apocynaceae, comes in many shapes, sizes, and lifestyles. From the open-field milkweeds we are most familiar with here in North America to the cactus-like Stapeliads of South Africa, it would seem that there is no end to the adaptive abilities of this family. Being an avid gardener both indoors and out, the diversity of Apocynaceae means that I can be surrounded by these plants year round. My endless quest to grow new and interesting houseplants was how I first came to know a genus within the family that I find quite fascinating. Today I would like to briefly introduce you to the Dischidia vines.

The genus Dischidia is native to tropical regions of China. Like its sister genus Hoya, these plants grow as epiphytic vines throughout the canopy of warm, humid forests. Though they are known quite well among those who enjoy collecting horticultural curiosities, Dischidia as a whole is relatively understudied. These odd vines do not attach themselves to trees via spines, adhesive pads, or tendrils. Instead, they utilize their imbricated leaves to grasp the bark of the trunks and branches they live upon.

The odd, bulb-like leaves of the urn vine (Dischidia rafflesiana) Photo by Bernard DUPONT licensed under CC BY-SA 2.0

One thing we do know about this genus is that most species specialize in growing out of arboreal ant nests. Ant gardens, as they are referred to, offer a nutrient rich substrate for a variety of epiphytic plants around the world. What's more, the ants will visciously defend their nests and thus any plants growing within.

The flowers of Dischidia ovata Photo by Krzysztof Ziarnek, Kenraiz licensed under CC BY-SA 4.0

Some species of Dischidia take this relationship with ants to another level. A handful of species including D. rafflesiana, D. complex, D. major, and D. vidalii produce what are called "bullate leaves." These leaves start out like any other leaf but after a while the edges stop growing. This causes the middle of the leaf to swell up like a blister. The edges then curl over and form a hollow chamber with a small entrance hole.

Photo by Krzysztof Ziarnek, Kenraiz licensed under CC BY-SA 4.0

These leaves are ant domatia and ant colonies quickly set up shop within the chambers. This provides ample defense for the plant but the relationship goes a little deeper. The plants produce a series of roots that crisscross the inside of the leaf chamber. As ant detritus builds up inside, the roots begin to extract nutrients. This is highly beneficial for an epiphytic plant as nutrients are often in short supply up in the canopy. In effect, the ants are paying rent in return for a place to live.

Growing these plants can take some time but the payoff is worth. They are fascinating to observe and certainly offer quite a conversation piece as guests marvel at their strange form.

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

Further Reading: [1]

This Isn't Even My Final Form! A Pothos Story

Photo by Forest and Kim Starr licensed under CC BY 2.0

Pothos might be one of the most widely cultivated plants in modern history. These vining aroids are so common that I don't think I can name a single person in my life that hasn't had one in their house at some point or another. Renowned for their hardy disposition and ability to handle extremely low light conditions, they have become famous the world over. They are so common that it is all too easy to forget that they have a wild origin. What's more, few of us ever get to see a mature specimen. The plants living in our homes and offices are mere juveniles, struggling to hang on as they search for a canopy that isn't there.

Trying to find information on the progenitors of these ubiquitous houseplants can be a bit confusing. To do so, one must figure out which species they are talking about. Without a proper scientific name, it is nearly impossible to know which plant to refer to. Common names aside, pothos have also undergone a lot of taxonomic revisions since their introduction to the scientific community. Also, what was thought to be a single species is actually a couple.

Photo by Forest and Kim Starr licensed under CC BY 2.0

To start with, the plants you have growing in your home are no longer considered Pothos. The genus Pothos seemed to be a dumping ground for a lot of nondescript aroid vines throughout the last century. Many species were placed there until proper materials were thoroughly scrutinized. Today, what we know as a "Pothos" has been moved into the genus Epipremnum. This revision did not put all controversies to rest, however, as the morphological changes these plants go through as they age can make things quite tricky.

Photo by Tauʻolunga licensed under CC BY-SA 3.0

As I mentioned, the plants we keep in our homes are still in their juvenile form. Like all plants, these vines start out small. When they find a solid structure in a decent location, they make their bid for the canopy. Up in a tree in reach of life giving sunlight, these vines really hit their stride. They quickly grow their own version of a canopy that consists of massive leaves nearing 2 feet in length! This is when these plants begin to flower. 

As is typical for the family, the inflorescence consists of a spadix covered by a leafy spathe. The spadix itself is covered in minute flowers and these are the key to properly identifying species. When pothos first made its way into the hands of botanists, all they had to go on were the small, juvenile leaves. This is why their taxonomy had been such a mess for so long. Materials obtained in 1880 were originally named Pothos aureus. It was then moved into the genus Scindapsus in 1908.

Controversy surrounding a proper generic placement continued throughout the 1900's. Then, in the early 1960's, an aroid expert was finally able to get their hands on an inflorescence. By 1964, it was established that these plants did indeed belong in the genus Epipremnum. Sadly, confusion did not end there. The plasticity in forms and colors these vines exhibit left many confusing a handful of species within the group. At various times since the late 1960's, E. aureum and E. pinnatum have been considered two forms of the same species as well as two distinct species. The latest evidence I am aware of is that these two vines are in fact distinct enough to warrant species status. 

Photo by Mokkie licensed under CC BY-SA 3.0

The plant we most often encounter is E. aureum. Its long history of following humans wherever they go has led to it becoming an aggressive invader throughout many regions of the world. It is considered a noxious weed in places like Australia, Southeast Asia, India, Pakistan, and Hawai'i (just to name a few). It does so well in these places that it has been a little difficult to figure out where these plants originated. Thanks to some solid detective work, E. aureum is now believed to be native to Mo'orea Island off the west coast of French Polynesia. 

Epipremnum pinnatum is similar until you see an adult plant. Photo by Mokkie licensed under CC BY-SA 3.0

It is unlikely that most folks have what it takes to grow this species to its full potential in their home. They are simply too large and require ample sunlight, nutrients, and humidity to hit their stride. Nonetheless there is something to be said for the familiarity we have with these plants. They have managed to enthrall us just enough to be a fixture in so many homes, offices, and shopping centers. It has also helped them conquer far more than the tiny Pacific island on which they evolved. Becoming an invasive species always seems to have a strong human element and this aroid is the perfect example.

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

Further Reading: [1] [2] [3] 

A Surprising Realization About Leaf Windows

I will never forget the first time I laid eyes on a Lithops. These odd little succulents are truly marvels of evolution. The so-called "living stones" really do earn their name as most are exquisitely camouflaged to match the gravelly soils in which they grow. If bizarre color patterns weren't enough, Lithops, as well as many other succulents, live their lives almost completely buried under the soil. All one ever really sees is the very tip of their succulent leaves and the occasional flower.

It is the tips of those leaves that make people swoon. Lithops belong to a hodgepodge mix of succulent genera and families that produce windowed leaves. Aside from their striking patterns, the tips of their leaves are made up of layers of translucent cells, which allow light to penetrate into the interior of the leaf where the actual photosynthetic machinery is housed. Their semi-translucent leaves, coupled with their nearly subterranean habit, have led to the assumption that the leaf windows allow the plants to continue photosynthesis all the while being mostly buried. Despite the popularity of this assumption, few tests had been performed to see whether or not the windows function as we think. All of that changed back in the year 2000.

As hinted at above, a variety of succulent plants have converged on a similar leaf morphology. This is where things get a bit strange. Not all plants that exhibit the leaf window trait find themselves buried in the soil. Others, such as Peperomia graveolens for example, produce the photosynthetic tissues on tall stems. Examples like this led at least some researchers to second guess the common assumption of windows increasing photosynthesis and the resulting investigations were surprising to say the least. 

Peperomia graveolens. © Raimond Spekking / CC BY-SA 4.0 (via Wikimedia Commons)

A duo of researchers decided to test the assumption that leaf windows increase photosynthesis by channeling light directly to the photosynthetic machinery inside. The researchers used tape to cover the leaf windows of a variety of succulent plant species. When they compared photosynthetic rates between the two groups, not a single difference was detected. Plants who had their leaves covered photosynthesized the same amount as plants with uncovered leaves. These data were quite shocking. Because they tested this assumption across a variety of plant species, the results suggested that the function of windowed leaves isn't as straight forward as we thought. These findings raised more questions than they solved.

Subsequent experiments only served to reinforce the original findings. What's more, some even showed that plants with covered windows actually photosynthesized more than plants with uncovered windows. It seems that windowed leaves function in a completely opposite manner than the popular assumption. The key to this patterns may lie in heat exchange. When the researchers took the temperature of the interior of the leaves in each group, they found that internal leaf temperatures were significantly higher in the uncovered group and this has important implications for photosynthesis for these species.

High leaf temperatures can be extremely damaging to photosynthetic proteins. If too much light filters through, leaf temperatures can actually hit damaging levels. This is one reason that many of these plant species have adopted this bizarre semi-subterranean habit. Plants that experienced such high temperatures throughout the course of a day had permanent damage done to their photosystems. This led to a reduction of fitness over time. Such lethal temperature spikes did not happen to leaves that had been covered.

Haworthia truncata. Photo by www.haworthia-gasteria.com

If you're anything like me, at this point you must be questioning the role of the leaf windows entirely. Why would they be there if they may actually hurt the plants in the long run? Well, this is where knowing something about the habitat of each species comes into play. Not all leaf windows are created equal. The patterns of their windows vary quite a bit depending on where the plants evolved. In 2012, a paper was published that looked at the patterns of Lithops leaf windows in relation to their place of origin. Not all Lithops grow in the same conditions and various species hail from regions with vastly different climates.

What the paper was able to demonstrate was that Lithops native to regions that experience more average annual rainfall have much larger window areas on their leaves than Lithops native to drier regions. Again, the underpinnings of this discovery nonetheless have to do with light availability. Wetter areas experience more cloud cover than drier areas so Lithops growing where its cloudy have to cope with a lot less sun than their more xeric-growing cousins. As such, having a larger window allows more diffuse light into the leaf for photosynthesis without having to worry about the damaging temperatures.

Photo by Petra licensed under CC BY-NC 2.0

The reverse is true for Lithops from drier climates. They have smaller leaf windows because they experience more days with direct sun. Smaller windows means less sunlight entering the leaf. This serves to keep internal leaf temperatures within a much safer range, thus protecting the delicate proteins inside. As it turns out, leaf windows seem to represent a trade-off between photosynthesis and overheating. What's more, some window-leaved species seem to be evolving away from the light transmitting function of their cousins living in shadier conditions. If anything, this serves as a reminder that simply because something seems obvious, that doesn't mean its always true. Stay curious, my friends!

Photo Credits: [1] [2] [3] [4] [5] [6]

Further Reading: [1] [2] [3] [4] [5] [6]

Poinsettias Wild Origins

Photo by Dinesh Valke licensed under CC BY-SA 2.0

Poinsettias are famous the world over for the splash of color they provide indoor spaces during the colder months of the year. The name "poinsettia" is seemingly synonymous with the holiday season. They are so common that it is all too easy to write them off as another disposable houseplant whose only purpose is to dazzle us with a few short weeks of reds and whites. With all of the focus on those colorful bracts, it is also easy to lose sight of the fact that these plants have wild origins. What exactly is a poinsettia and where do they come from?

Poinsettia is the common name given to a species of shrub known scientifically as Euphorbia pulcherrima. No one quite knows the exact origin of our cultivated house guests but the species itself is native to the mountains of the Pacific slope of Mexico. It is a scraggly shrub that lives in seasonally dry tropical forests. Mature specimens can grow to be so large and lanky that they almost resemble vines. As many of you know, the poinsettias we use to decorate our homes never reach the same sizes as their wild counterparts. The reason for this is because all cultivated poinsettias have been purposely infected with a bacteria that stunts their growth, keeping them small and compact.

Photo by Frank Vincentz licensed under CC BY-SA 3.0

These shrubs flower throughout winter and into spring. What we think of as large, showy, red and white flower petals are not petals at all. They are actually leafy bracts. Like a vast majority of Euphorbia species, E. pulcherrima produces a special type of inflorescence called a cyathium. The flowers themselves are small, yellow, and not much to look at with the naked eye. However, take a hand lens to them and you will reveal rather intriguing little structures. What the flowers lack in showy display is made up for by the colorful bracts, which serve similar functions as petals in that their stunning colors are there to attract potential pollinators. 

Those bracts also caught the attention of horticulturists. Because of their beauty, E. pulcherrima is one of the most widely cultivated plants in human history. As many a poinsettia owner has come to realize, the bracts do not stay colored up all year. In fact, the whole function of these bracts is to save energy on flower production by coloring up leaves that are already in place. If they don’t have to produce pigments, they won’t and for much of the year, the bracts are largely green. The key to the color change lies in Earth’s axial tilt.

Photo by Gavin White licensed under CC BY-NC-ND 2.0

As the northern hemisphere begins to tilt away from the sun, days grow shorter. In turn, poinsettia plants begin to mature their flowers. At the same time, changes within the leafy bracts cause them to start producing pigments. When the days become shorter than the nights, the plants go into full reproductive mode. Both red- and white-colored bracts have been found in the wild. As soon as the days start to grow longer than the nights, the plants switch out of reproductive mode and the dazzling color fades. In captivity, this change is mimicked by plunging plants into complete darkness for a minimum of 12 hours per day.

Photo by Kahunapule Michael Johnson licensed under CC BY-NC-SA 2.0

Another aspect worth considering about this species is its sap. Whereas most plants hailing from Euphorbiacea or spurge family contain toxic sap, the sap of E. pulcherrima is very mild in its toxicity and an absurd amount of plant material would have to be consumed to suffer any serious side effects. Certainly it serves an anti-herbivore purpose in the wild, however, as long as you're not a tiny insect or a gluttonous deer, you have nothing to worry about from this species at least. So there you have it, some food for thought if you feel the urge to purge some spurge in a post-holiday cleanse. Condsider keeping these wonderful plants in your home for another year. If you follow their natural daylight cycle, you may just coax some color out of them for many winters to come.

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

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

This Is Not The Bamboo You Are Looking For...

Photo by Benoit Giroux licensed under CC BY-NC-SA 2.0

She has one, he has one, you have one, I have one, the office has one... lets just say "lucky bamboo" has made its way into many a home, office, and waiting room. Popularized by the practice of feng shui and sold for pennies on the dime by New Age stores all over the world, these plants seem to thrive on neglect. It may come as a surprise then that these plants are not a bamboo at all.

These ubiquitous home decorations are actually a species of Dracaena, Dracaena braunii to be exact. It isn't even from the same taxonomical order as bamboo. Whereas bamboo are a type of grass, D. braunii is actually more closely related to lilies. Hailing from Africa, D. braunii grows as an understory shrub in rainforests. This may explain why it does so well in the nutrient poor, low light conditions of most homes. 

In the wild, it can grow upwards of 5 feet tall. In captivity, however, it rarely exceeds 3 feet.. While most people grow theirs in a container of water and pebbles, D. braunii can do equally as well, if not better in potting mix.

Photo Credit: Benoit Giroux

Further Reading: [1]

The Benefits of Houseplants

I don't know about you, but I find indoor gardening to be just as satisfying and intellectually stimulating as any amount of outdoor gardening. Coming from a temperate climate, I don't think I would be able to survive the long winters if it were not for my houseplants. The benefits to keeping plants in the home as well as the office are numerous and range the spectrum from improving air quality to diminishing stress and aiding in healing.

Few would probably argue that a room with plants in it feels far more lived in and hospitable than an empty, sterile room. It makes sense. We evolved, like everything else on this planet, in a natural setting filled with seemingly endless varieties of different plant species. It should be no surprise that our minds would be more at ease the more natural any environment seems. Studies have shown that in an indoor work environment, offices that contained plants had statistically significant reductions in employee discomfort, stress, and an increase in their overall well being. It doesn't end at work either. Hospitals and other medical facilities also showed that overall well being improved both physically and mentally with their residents. In patients suffering from dementia, indoor plants are said to "stimulate residents’ senses, created positive emotions, and offered opportunity for rewarding activity."

Plants do so much more than just improve our moods and reduce stress, they also clean the air we breath. Many every-day household items off-gas some pretty nasty chemicals. Insulation, particle board, PVC and vinyl, carpets, flooring, even our own clothing, all of these things come with their own gaseous and particulate chemical cocktails. It has been shown time and time again that many species of commonly kept house plants help to remove these molecules from the home environment. Some species are better than others. For instance, spider plants (genus Chlorophytum), are exceptionally good at removing formaldehyde compounds in the air. A room full of plants also exhibits statistically significant reductions in particulate matter as well as a measurable increase in humidity levels.

Whether they make you feel at ease or because they clean the air you breath, having house plants is a good thing. There are many species that are available both in nurseries as well as online. Some of the best plants for the home are also the most sensibly priced. Get online and do some research. There are a lot of easy plants to care for out there if you don't necessarily have a green thumb.

Further Reading: [1] [2] [3] [4] [5] [6] [7]

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:

Time

There is something very special about old plants. They offer us a way of appreciating a timescale that we can never fully understand. I am especially fond of finding people who have had house plants in their family for generations. I grew up with a few that had already been around for decades before I was born. Here is a wonderful example of what I am talking about. This Acronia titan orchid has been blooming for years and has acquired a wonderful little moss patch in the crux of its leaf. Out of that moss grows a fern.

This photo comes to us courtesy of Kevin Holcomb. You can find him on instagram via @orchid_beard

Common Yet Endangered Palms

Raise you hand if you have ever had a parlor palm (Chamaedorea elegans). I see most of you have raised your hands. Palms in the genus Chamaedorea are the most commonly kept palms on the market. They are small, very shade tolerant, and nearly indestructible. The clear winner in this regard is the parlor palm. We have all given these little palms a shot at one time or another. They are so common that we rarely give a second thought as to where they come from. Surely they did not evolve in a nursery. It may surprise you that for as ubiquitous as these palms are, they are actually quite threatened in the wild.

The genus Chamaedorea is endemic to sub-tropical forests of the Americas and is comprised of roughly 80 species. They are understory palms that are most at home under the deep shade of the canopy. Most species are generally pretty small, rarely growing over 10 feet. All of these factors add up to some resilient and fun houseplants. It doesn't take much to keep them happy. Every once in a while they will produce flowers. Though small, they are often brightly colored. The preferred method for mass cultivation is via seed. However, seed production outside of their native range is notoriously difficult and often requires human intervention. For this reason, a vast majority of nursery grown palms are grown from wild collected seeds.

This may not seem like a bad deal until you look at the numbers. I have seen reports of over 500 million seeds exported from Mexico annually. Couple this with the fact that many species of Chamaedorea are known to grow in very restricted ranges and suddenly the picture becomes very bleak. Over collecting of seeds has decimated wild populations. Without seeds there is no recruitment, no seedlings to take the place of adult plants.

Another considerable threat to these palms comes from the cut flower industry. Palm fronds are notoriously gorgeous and many people like to include them in their displays. Most of the leaves cut come from wild plants. Normally palm fronds are harvested in a manner that doesn't kill the plant, however, in Mexico children are often employed to collect them and their lack of experience can severely damage wild populations.

On top of all of this, the forests in which these palms grow are now being converted to agriculture. If actions are not taken to limit the abuse of wild populations, it is likely that some of the most commonly encountered house plants are going to be extinct in the wild. This is a hard pill to swallow. If you have any of these species growing in your home, take care of them. Perhaps knowing how uncertain the future is for many of these palms will earn them a little more respect.

Here is a list of some of the most threatened species in this genus:

Chamaedorea amabilis
Chamaedorea klotzschiana
Chamaedorea metalica
Chamaedorea pumila
Chamaedorea sullivaniorum
Chamaedorea tuerckheimii

Photo Credits: Michael Wolf (http://bit.ly/16suMsf), scott.zona (http://bit.ly/1zHdUII),

Further Reading:
http://bit.ly/1ADC3mw

Plant Bits

Begonia cultivar

Epidendrum denticulatum 

Unknown fern

Euphorbia sp. 

Crassula sp.  

Oncidium sp.  

Cast In Iron

Photo by Phillip Merritt licensed under CC BY-NC-SA 2.0

When it comes to hardy houseplants, few species can hold a candle to the Aspidistra. With their ability to tolerate dismal lighting conditions and less than stellar air quality, it is no wonder the this genus was a favorite among the middle class during the Victorian era. They were so common during that time period that George Orwell himself used them as a metaphor in his 1936 novel "Keep the Aspidistra Flying." Today they are nothing more than space fillers. Commonly known as "cast iron plants," they are a natural step up from silken foliage in waiting rooms and cubicles. They can virtually be ignored and still maintain their composure. For a houseplant, this is pretty incredible. However, this genus did not originate in the home. It is just as wild as any other plant out there. What are the Aspidistra and where do they come from?

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

With their long, strap-like leaves that seem to pop out of the dirt at random, it is not readily apparent that these plants belong to the same family as asparagus - Asparagaceae. Since the 1980's, botanists have described upwards of 93 different species within the genus. They are native to eastern Asia and hit their peak diversity in China and Vietnam. Many species within this genus are endemic to these areas. 

Photo by Scott Zona licensed under CC BY-NC 2.0

Aspidistra as a whole are understory species, growing on the ground underneath dense canopies of trees and shrubs. This is why they can adapt so well to the low light conditions of homes and offices. Though they are mostly tropical in nature, Aspidistra have been known to cope with temperatures as low as −5 °C (23 °F). Despite their leafy appearance, Aspidistra have surprisingly beautiful flowers. You just have to know where to look. 

Flowers are produced at the base of the plant. They are often covered by litter and soil. Despite their cryptic nature, they are nonetheless incredibly beautiful and complex. The flowers are spider-like with a large flattened stigma. They are also the key to identifying different species. Their pollinators are thought to consist mostly of flies, beetles, and the occasional fungus gnat. There is some evidence that some species of Aspidistra are even pollinated by amphipods in the soil. If this is true, it is surely one of the most unique pollinator syndromes ever discovered. 

So, there you have it. One of the most commonly kept and ignored houseplants just happens to be quite interesting. Every plant has an evolutionary and ecological history that has shaped its kind over millennia. It just goes to show you that even the most common houseplants have a story to tell. Think about that next time you come across these growing in a stuffy waiting room. 

Photo Credit: justinleif (http://bit.ly/1srlbwk), scott.zona (http://bit.ly/1wQMdcZ), Phillip Merritt (http://bit.ly/14Rcbph)

Further Reading: [1] [2] [3] [4] [5] [6]