Meet Virginia Pennywort

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

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

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

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

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

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

Begonia's Hawaiian Cousin

Photo by Forest and Kim Starr licensed under CC BY 2.0

Begoniaceae is a strange family. It consists of two genera - Begonia, which comprises roughly 1,400 species, and Hillebrandia, which consists of a single species endemic to Hawai'i (Symbegonia has since been placed back into Begonia). Although I adore the entire family, its that single genus that is the focus of our attention today. Far from being a strange one-off, Hillebrandia has a fascinating evolutionary history.

The sole species, Hillebrandia sandwicensis, is the only member of the family native to Hawai'i. It differs from the genus Begonia in characters such as its petals, which are more numerous and more differentiated, its ovaries, which do not completely close, as well as various morphological characteristics of its fruit and pollen, which I won't go into here. It occurs naturally only on the islands of Kauai, Maui, and Molokai where it inhabits wet ravines in montane rainforest zones. Nowhere is this species considered abundant. 

Since its discovery in 1866, H. sandwicensis has been the object of much curiosity. Where did it originate? How old of a species is it? How did it get to Hawai'i? Thanks to some molecular work, a few of these questions are becoming a bit more clear. For starters, we can now confidently say that Hillebrandia is a sister lineage to all other Begonias. This in turn has provided a crucial step in our understanding of its biogeography.

Photo by John Game licensed under CC BY 2.0

Molecular dating techniques place the genus Hillebrandia at about 51–65 million years old, much older than any of the Hawaiian islands. As such, it is likely that this lineage is not the results of an adaptive radiation like we see in most of the archipelago's flora and fauna. Instead, it is now believed that H. sandwicensis is the only known relict species in Hawaiian flora. In other words, the ancestor of H. sandwicensis did not arrive at Hawai'i and then evolve into the species we know today. Instead, it is more likely that the lineage arose elsewhere and then, through a random long-distance seed dispersal event, made it to Hawai'i's oldest islands some 30 million years ago and has been island hopping to younger islands ever since. 

Although its recent history and geographic origins are still open to much speculation, the story of this unique genus has gotten a bit clearer. Its status as Hawai'i's only known relict plant species is quite exciting to say the least. What we can say for sure is that its history was likely full of serendipity that should be celebrated each time someone has an encounter with this lovely Hawaiian plant.

Photo Credits: [1] [2]

Further Reading: [1]

The Hunt

This week we are going on the hunt for a small member of the carrot family known as the harbinger of spring (Erigenia bulbosa). Along the way we meet a handful of interesting plant species. Will we find our quarry? Watch and find out...

Producer, Writer, Creator, Host:
Matt Candeias (www.indefenseofplants.com)

Producer, Editor, Camera:
Grant Czadzeck (www.grantczadzeck.com)

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Tumblr: www.tumblr.com/indefenseofplants

Twitter: @indfnsofplnts

Early Spring Botanizing

SURPRISE!

Many have commented that a video component was lacking from the hiking podcasts. I have teamed up with filmmaker/producer Grant Czadzeck (www.grantczadzeck.com) to bring you a visual botanizing experience. I'm not sure how regular this will become but let us know what you think. In the mean time, please enjoy this early spring hike in central Illinois.

Thanks, Ducks!

Photo by loren chipman licensed under CC BY-NC 2.0

Recent research suggests that certain duck species are crucial for maintaining wetland plant diversity in highly fragmented landscapes. Functioning wetlands are becoming more and more isolated each year. As more land is gobbled up for farming and development, the ability for plants to get their seeds into new habitats is made even more difficult. Luckily, many plants utilize animals for this job. Seeds can become stuck in fur or feathers, and some can even pass through the gut unharmed. What's more, animals can move great distances in a short amount of time. For wetland plants, the daily movements of ducks seems to be paramount. 

By tracking the daily movements of mallards, a team of researchers from Utretch University were able to quantify how crucial these water fowl are for moving seeds around. What they found was quite remarkable. In autumn and winter, the diet of mallards switches over to seeds. Not all seeds that a mallard eats get digested. Many pass through the gut unharmed. Additionally, mallards are strong flyers. On any given day they can travel great distances in search of winter foraging grounds. In the evenings, they return to roosting sites with a high degree of fidelity. 

[SOURCE]

The research team was able to demonstrate that their movements cover even greater distances in highly fragmented landscapes. It's these daily migrations that are playing a major role in maintaining plant diversity between distant wetlands. This is especially important for wetlands that function as roost sites. Whereas mallards distribute around 7% of the surviving seeds they eat among foraging sites, that number jumps to 34% for surviving seeds at roost sites. Given the sheer number of mallards on the landscape, these estimates can really add up. 

It is likely that without mallards, North American wetlands would be much less diverse given their increasingly isolated nature. However, not all seeds are dispersed equally. Small seeds are far more likely to pass through the gut of a duck unharmed, meaning only a portion of the plant species that grow in these habitats are getting a helping hand (wing?). Still, the importance of these birds cannot be overlooked. The next time you see a mallard, thank it for maintaining wetland plant diversity. 

Photo Credits: [1] [2]

Further Reading: [1]

Spring Has Sprung Earlier

Phenology is defined as "the study of cyclic and seasonal natural phenomenon, especially in relation to climate, plant, and animal life." Whether its deciding when to plant certain crops or when to start taking your allergy medication, our lives are intricately tied to such cycles. The study of phenology has other applications as well. By and large, it is one of the best methods we have in understanding the effects of climate change on ecosystems around the globe. 

For plants, phenology can be applied to a variety of things. We use it every time we take note of the first signs of leaf out, the first flowers to open, or the emergence of insect herbivores.  In the temperate zones of the world, phenology plays a considerable role in helping us track the emergence of spring and the onset of fall. As we collect more and more data on how global climates are changing, phenology is confirming what many climate change models have predicted - spring is starting earlier and fall is lasting longer.

Researchers at the USA National Phenology Network have created a series of maps that illustrate the early onset of spring by using decades worth of data on leaf out. Leaf out is controlled by a variety of factors such as the length of chilling temperatures in winter, the rate of heat accumulation in the spring, and photoperiod. Still, for woody species, the timing of leaf out is strongly tied to changes in local climate. And, although it varies from year to year and from species to species, the overall trend has been one in which plants are emerging much earlier than they have in the past.

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https://www.usanpn.org/data/spring

For the southern United States, the difference is quite startling. Spring leaf out is happening as much as 20 days earlier than it has in past decades. Stark differences between current and past leaf out dates are called "anomalies" and the 2017 anomaly in the southern United States is one of the most extreme on record.

How this is going to alter ecosystems is hard to predict. The extended growing seasons are likely to increase productivity for many plant species, however, this will also change competitive interactions among species in the long term. Early leaf out also comes with increased risk of frost damage. Cold snaps are still quite possible, especially in February and March, and these can cause serious damage to leaves and branches. Such damage can result in a reduction of productivity for these species.

Changes in leaf out dates are not only going to affect individual species or even just the plants themselves. Changes in natural cycles such as leaf out and flowering can have ramifications across entire landscapes. Mismatches in leaf emergence and insect herbivores, or flowers and pollinators have the potential to alter entire food webs. It is hard to make predictions on exactly how ecosystems are going to respond but what we can say is that things are already changing and they are doing so more rapidly than they have in a very long time. 

For these reasons and so many more, the study of phenology in natural systems is crucial for understanding how the natural world is changing. Although we have impressive amounts of data to draw from, we still have a lot to learn. The great news is that anyone can partake in phenological data collection. Phenology offers many great citizen science opportunities. Anyone and everyone can get involved. You can join the National Phenology Network in their effort to track phenological changes in your neighborhood. Check out this link to learn more: USA National Phenology Network

Further Reading: [1] [2]  

Carnations Revealed

Photo by Zeynel Cebeci licensed under CC BY-SA 3.0

Confession: over-bred, multi-petaled carnations make me want to puke. I find them monstrously gaudy. I don't like feeling this way towards a plant. It isn't the plants fault that we turned it into such a mutant. So, today I though I would dedicate this space to honoring the wild congener of the domestic carnation.

When we talk about carnations we are referring to cultivars of the genus Dianthus. The most prominent cultivars we see today originated from Dianthus caryophyllus. It is hard to pinpoint the native origin of this species as it has been cultivated throughout Europe and Asia for upwards of 2000 years. Regardless, it is thought that the wild carnation is native to a stretch of the Mediterranean region encompassing Greece and Italy.

Wild carnations are more sleek in appearance than their cultivated cousins. They are modest sized plants each producing flowers with five serrated petals that range in color from white to pink. The flowers are protandrous meaning the male parts mature and senesce before the female parts. This helps to reduce inbreeding. Nectaries are located at the base of the flower and it is thought that long tongued bees and lepidotera take up the bulk of pollination services.

Following pollination, the petals begin to produce ethylene gas. This causes near complete collapse of the flowers within 24 hours. Why bother wasting energy on expensive floral parts that can now be directed to seed production? Upon maturity, the seed capsule breaks open at the top. Its position at the tip of the stem allows for a combination of ballistic and wind seed dispersal. As the capsule sways back and forth in the breeze, the tiny seeds are launched from the capsule like shrapnel from a catapult.

The multi-petaled mutants we have selectively bred barely function as viable plants anymore. In the wild, carnations are perennial, producing one to six flowers a season and plenty of seeds. Because we value looks and longevity over biology, cultivated carnations will often flower themselves to death in one season. Also, the duplication of petals has made it so that insects cannot reach the interior to get at the pollen or nectar, removing a great deal of their potential ecological value.

Dianthus caryophyllus isn't alone in this genus. Over 300 species of Dianthus have been described each with their own ecology and distribution. They range in appearance from modesty creeping herbs to woody shrub-like plants. Many of these have been utilized by plant breeders to create new cultivars. Unfortunately this is yet another genus of plants whose cultivars get all the attention.

Photo Credit: [1]

Further Reading: [1] [2]

Pollination with a Twist

[SOURCE]

Ensuring that pollen from one flower makes it to another flower of that species is paramount to sexual reproduction in plants. It's one of the main drivers of the diversity in shapes, sizes, and colors we see in flowers across the globe. Sometimes the mechanism isn't so obvious. Take, for instance, the flowers of Impatiens frithii.

The flowers of this Cameroonian endemic have been a bit of a puzzle since its discovery. Like all Impatiens, they have a long nectar spur. However, the spur on I. frithii is uniquely curved. This puzzled botanists because most of the Impatiens in this region are pollinated by sunbirds. The curved spur would appear to make accessing the nectar within quite difficult for a bird. Still, just because we can't imagine it, doesn't mean that it's impossible. Something must pollinate this lovely little epiphyte in one way or another. This is where close observation comes in handy.

Thanks to remote cameras and lots of patience, botanists were able to record pollination events. They quickly realized that sunbirds are indeed the primary pollinator of this species. This was a bit of a surprise given the shape of the flower. However, the way in which the flowers deposit pollen on this birds is what is most remarkable. As it turns out, successful reproduction in I. frithii all comes down to that curved nectar spur. 

When a sunbird probes the flower for nectar, its beak follows the contour of the spur and this causes the entire flower to twist. As it twists, the anthers and stigma make contact with the chin of the bird. This is unlike other Impatiens which deposit the pollen on top of the heads of visiting birds.

Such an adaptation is quite remarkable in many ways. For one, it is elegantly simple. Such a small alteration of floral architecture is all that is required. Second, by placing pollen on the underside of the head, the plant guarantees that only pollen from its species will ever come into contact with the stigma. This is what we call reproductive isolation, which is an important driver in speciation.

Photo Credit: [1]

Further Reading: [1]

Convergent Carnivores

Photo by Natalie McNear licensed under CC BY-NC 2.0

A carnivorous lifestyle has evolved independently in numerous plant lineages. Despite the similarities between genera like Nepenthes, Sarracenia, and Cepholotus they are not closely related. Researchers have wondered how the highly modified leaves of various carnivorous plant species evolved into the insect trapping and digesting organs that we see today. Thanks to a recent article published in Nature, it has been revealed that the mechanisms responsible for carnivory in plants are a case of convergent evolution.

This research all started with the Australian pitcher plant Cepholotus follicularis. More closely related to wood sorrels (Oxalis spp.) than either of the other two pitcher plant families, this species offers a unique window into the genetic controls on pitcher development. Cepholotus produces two different kinds of leaves - normal, photosynthetic leaves and the deadly pitcher leaves that have made it famous the world over.

By observing which genes are activated during the development of these different types of leaves, the research team was able to identify which alleles have been modified. In doing so, they were able to identify genes involved in producing the nectar that attracts their insect prey as well as the genes involved in producing the slippery waxy coating that keeps trapped insects from escaping. But they also found something even more interesting.

[SOURCE]

By examining the digestive fluids produced by Cepholotus as well as many other unrelated carnivorous plant species from around the world, researchers made a startling discovery. They found that the genes involved in synthesizing the deadly digestive cocktails among these disparate lineages have a similar evolutionary origin.

Although they are unrelated, the ability to digest insects seems to have its origins in defending plants against fungi. You have probably heard someone say that fungi are more similar to animals than they are plants. Well, the polymer that makes up the cell walls of fungi is the same polymer that makes up the exoskeleton of insects - chitin. By comparing the carnivorous plant genes to those of the model plant Arabidopsis, the team found that similar genes became active when plants were exposed to fungal pathogens.

It appears that carnivorous plants around the world have all converged on a system in which genes used to defend themselves against fungal infection have been co-opted to digest insect bodies. Taken together, these results show that the path to carnivory in plants is surprisingly narrow. Evolution doesn't always require the appearance of new alleles but rather a retooling of genes that are already in place. 

Photo Credits: [1] [2]

Further Reading: [1]

On Fungi and Forest Diversity

One simply can't talk about plants without eventually talking about fungi. The fact of the matter is the vast majority of plant species rely on fungal interactions for survival. This mutualistic relationship is referred to as mycorrhizal. Fungi in the soil colonize the root system of plants and assist in the acquisition of nutrients such as nitrogen and phosphorus. In return, most photosynthetic plants pay their mycorrhizal symbionts with carbohydrates. 

There are two major categories of mycorrhizal fungi - ectomycorrhizae (EMF) and arbuscular mycorrhizae (AMF). Though there are a variety of different species of fungi that fall into either of these groups, their strategies are pretty much the same. EMF make up roughly 10% of all the known mycorrhizal symbionts. The prefix "ecto" hints at the fact that these fungi form on the outside of root cells. They form a sort of sheath that encases the outside of the root as well as a "hartig net" around the outside of individual cells within the root cortex. AMF, on the other hand, literally penetrate the root cells and form two different kinds of structures once inside. One of these structures looks like the crown of a tree, hence the term "arbuscular." What's more, they are considered the oldest mycorrhizal group to have evolved. 

[SOURCE]

The type of mycorrhizal fungi a plant partners with has greater implications that simple nutrient uptake. Evidence is now showing that the dominant fungi of a region can actually influence the overall health and diversity forest ecosystems. The mechanism behind this has a lot to do with the two different categories discussed above. 

Researchers have discovered that trees partnering with AMF experience negative feedbacks in biomass whereas those that partner with EMF experience positive feedbacks in biomass. When grown in soils that previously harbored similar tree species, trees that partnered with AMF grew poorly whereas trees that partnered with EMF grew much better. Additionally, by repeating the experiments with seedlings, researchers found that seedling survival was reduced for AMF trees whereas seedling survival increased in EMF trees. 

What is going on here? If mycorrhizae are symbionts, why would there be any detrimental effects? The answer to this may have something to do with soil pathogens. Thinking back to the major differences between EMF and AMF, you will remember that it comes down to the way in which they form their root associations. EMF form a protective sheath around the roots whereas AMF penetrate the cells.  As it turns out, this has major implications for pathogen resistance. Because they form a sheath around the entire root, EMF perform much better at keeping pathogens away from sensitive root tissues. The same can't be said for AMF. Researchers found that AMF trees experienced significantly more root damage when grown in soils that previously contained AMF trees. 

The differences in the type of feedback experienced by EMF and AMF trees can have serious consequences for tree diversity. Because EMF trees are healthier and experience increased seedling establishment in soils containing other EMF species, it stands to reason that this would lead to a dominance of EMF species, thus reducing the variety of species capable of establishing in that area. Conversely, areas dominated by AMF trees may actually be more diverse due to the reduction in fitness that would arise if AMF trees started to dominate. Though they are detrimental, the negative feedbacks experienced by AMF trees may lead to healthier and more diverse forests in the grand scheme of things. 

Infographic by [1]

Further Reading: [1]

Semi-Aquatic Orchids

By Jim Fowler. Copyright © 2017

Orchids have conquered nearly every continent on this planet except for Antarctica. In fact, there seems to be no end to the diversity in color, form, and habit of the world's largest family of flowering plants. Still, it might surprise many to learn that some orchids have even taken to water. Indeed, at least three species of orchid native to Latin and North America as well as a handful of islands have taken up a semi-aquatic lifestyle.

Most commonly encountered here in North America is the water spider orchid (Habenaria repens). It is a relatively robust species, however, considering that even its flowers are green, it is often hard to spot. Though it will root itself in saturated soils along the shore, it regularly occurs in standing water throughout the southeast. Often times, it can be found growing amidst other aquatic plants like pickerel weed (Pontederia cordata) and duck potato (Sagittaria latifolia). Because it can reproduce vegetatively, it isn't uncommon to find floating mats of comprised entirely of this orchid.  

By Jim Fowler. Copyright © 2017

Living in aquatic habitats comes with a whole new set of challenges. One of these is exposure to a new set of herbivores. Crayfish are particularly keen on nibbling plant material. In response to this, the water spider orchid has evolved a unique chemical defense. Coined "habenariol," this ester has shown to deter freshwater crayfish from munching on its leaves and roots. Another challenge is partnering with the right fungi. Little work has been done to investigate what kinds of fungi these aquatic orchids rely on for germination and survival. At least one experiment was able to demonstrate that the water spider orchid is able to partner with fungi isolated from terrestrial orchids, which might suggest that as far as symbionts are concerned, this orchid is a generalist.

The flowers of the water spider orchid are relatively small and green. What they lack in flashiness they make up for in structure and scent. The flowers are quite beautiful up close. The slender petals and long nectar spur give them a spider-like appearance. At night, they emit a vanilla-like scent that attracts their moth pollinators. 

Photo Credits: Jim Fowler. Copyright © 2017 www.jfowlerphotography.com

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

Orchid Dormancy Mediated by Fungi

Photo by NC Orchid licensed under CC BY-NC 2.0

North America's terrestrial orchids seem to have mastered the disappearing act. When stressed, these plants can enter into a vegetative dormancy, existing entirely underground for years until the right conditions return for them to grow and bloom. Cryptic dormancy periods like this can make assessing populations quite difficult. Orchids that were happy and flowering one year can be gone the next... and the next... and the next...

How and why this dormancy is triggered has confused ecologists and botanists alike. Certainly stress is a factor but what else triggers the plant into going dormant? According to a recent paper published in the American Journal of Botany, the answer is fungal.

Orchids are the poster children for mycorrhizal symbioses. Every aspect of an orchid's life is dependent on these fungal interactions. Despite our knowledge of the importance of mycorrhizal presence in orchid biology, no one had looked at how the abundance of mycorrhizal fungi influenced the life history of these charismatic plants until now.

By observing the presence and abundance of a family of orchid associated fungi known as Russulaceae, researchers found that the abundance of mycorrhizal fungi in the environment is directly related to whether or not an orchid will emerge. The team focused on a species of orchid known commonly as the small whorled pogonia (Isotria medeoloides). Populations of this federally threatened orchid are quite variable and assessing their numbers is difficult.

The team found that the abundance of mycorrhizal fungi is not only related to prior emergence of these plants but could also be used as a predictor of future emergence. This has major implications for orchid conservation overall. It's not enough to simply protect orchids, we must also protect the fungal communities they associate with.

Research like this highlights the need for a holistic habitat approach to conservation issues. So many species are partners in symbiotic relationships and we simply can't value one partner over the other. If conditions change to the point that they no longer favor the mycorrhizal partner, it stands to reason that it would only be a matter of years before the orchids disappeared for good.

Photo Credit: NC Orchid

Further Reading: [1]

A Unique Passionflower Endemic to Costa Rica

I love small flowers, especially if they pack in a lot of detail. That's is why this passion flower caught my eye. Meet Passiflora boenderi, a charismatic vine endemic to a small region of Costa Rica. Apparently this species had been sitting around in herbaria for years under a different name. It wasn't until living specimens were observed that botanists realized it is a distinct species.

There is a lot to look at on this species. The flowers themselves are some of the smallest in the genus. They pack in all of the detail of a larger passion flower, just in miniature. The leaves are quite stunning as well. They're bilobed with a tinge of purple and covered in bright, orange-yellow spots. The spots themselves serve an important role in protecting this plant from herbivores.

The genus Passiflora is part of an intense evolutionary arms race with a genus of butterfly known as Heliconius. Their caterpillars feed on the foliage of passion flowers. As such, Passiflora have evolved a variety of means that help them to avoid the attention of gravid female butterflies. The orange spots on the leaves of P. boenderi are one such adaptation and they serve a dual function.

The first is a visual deterrent. Female Heliconius prefer to lay their eggs on caterpillar-free leaves. This makes sense. Why bother laying eggs where there will be ample competition for food. The spots mimic, both in size and shape, the appearance of Heliconius eggs. A female looking for a spot to lay will see these spots and move on to another plant. In addition to the visual mimicry, these spots also secrete nectar. The energy-rich nectar inevitably attracts ants, which viciously defend them as a food source. If a caterpillar (or any other herbivore fore that matter) were to start munching on the leaves, the ants quickly drive them off.

Because of its limited range, P. boebderi is under threat of extinction. Habitat destruction of its lowland habitat for palm oil, pineapples, and vacation resorts is an ongoing threat to the long term survival of this species and many others. I was fortunate enough to have encountered this plant growing in the Cliamtron at the Missouri Botanical Garden but I fear that if we keep on doing what we humans are so good at, botanical gardens may be the only place this species will be found growing in the not too distant future.

Further Reading: [1] [2]

The Longleaf Pine: A Champion of the Coastal Plain

As far as habitat types are concerned, the longleaf pine savannas of southeastern North America are some of the most stunning. What's more, they are also a major part of one of the world's great biodiversity hotspots. Sadly, they are disappearing fast. Agriculture and other forms of development are gobbling up the southeast coastal plain at a bewildering rate. For far too long we have ignored, or at the very least, misunderstood these habitats. Today I would like to give a brief introduction to the longleaf pine and the habitat it creates.

The longleaf pine (Pinus palustris) is an impressive species. Capable of reaching heights of 100 feet or more, it towers over a landscape that boggles the mind. It is a landscape born of fire, of which the long leaf pine is supremely adapted to dealing with. These pines start out life quite differently than other pines. Seedlings do not immediately reach for the canopy. Instead, young long leaf pines spend their first few years looking more like a grass than a tree. Lasting anywhere between 5 to 12 years, the grass stage of development gives the young tree a chance to save up energy before it makes any attempt at vertical growth. 

The reason for this is fire. If young long leaf pines were to start their canopy race immediately, they would very likely be burned to death before they grew big enough to escape the harmful effects of fire. Instead, the sensitive growing tip is safely tucked away in the dense needle clusters. If a fire burns through the area only the tips of the needles will be scorched, leaving the rest of the tree safe and sound. During this stage, the tree is busy putting down an impressive root system. The taproot alone can reach depths of 6 to 9 feet!

Once a hardy root system has been formed and enough energy has been acquired, young longleaf pines go through a serious growth spurt. Starting in later winter or early spring, the grass-like tuft will put up a white growth tip called a candle. This tip shoots upwards quite rapidly, growing a few feet in only a couple of months. This is sometimes referred to as the bottlebrush phase because no horizontal branches are formed during this time. The goal at this point is to get the sensitive growing tip as far away from the ground as possible so as to avoid damaging fires. It is fun to encounter long leaf pines at this stage because like any young adult, they look a bit awkward.

Photo Credit: Woodlot - Wikimedia Commons

Once the tree reaches about 6 to 10 feet in height, it will finally begin to produce horizontal branches. This doesn't stop its canopy bid, however, as it still will put on upwards of 3 feet of vertical growth each year! Every year its bark grows thicker and thicker, thus each year it becomes more and more resistant to fire. Far from being a force to cope with, fire unwittingly gives longleaf pines a helping hand by clearing the habitat of potential competitors that are less adapted to dealing with burns. After about 30 years of growth, longleaf pines reach maturity and will start to produce fertile cones.

Before European settlement, longleaf pine savanna covered roughly 90,000,000 acres of southeastern North America. Clearing and development have reduced that to a mere 5% of its former glory. For far too long its coastal plain habitat was thought to be a flat, monotonous region created by early human burning in the last few thousand years. We now know how untrue those assumptions are. Sure, the region is flat but it is anything but monotonous. Additionally, the coastal plain is one of the most lightning prone regions in North America. Fires would have been a regular occurrence long before any humans ever got there. 

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Red indicates forest loss between 2011 and 2014. http://glad.umd.edu/gladmaps

Evidence suggests that this coastal plain habitat has remained relatively stable for the last 62,000 years. As such, it is full of unique species. Surveys of the southeastern coastal plain have revealed multiple centers of plant endemism, rivaled in North America only by the southern Appalachian Mountains. In fact, taken together, the coastal plain forests are widely considered one of the world's biodiversity hotspots! Of the 62,000 vascular plants found in these forests, 1,816 species (29.3%) are endemic. Its not just plants either. Roughly 1,400 species of fish, amphibians, reptiles, birds, and mammals rely on the coast plain forests for survival.

Luckily, we are starting to wake up to the fact that we are losing one of the world's great biodiversity hotspots. Efforts are being put forth in order to conserve and restore at least some of what has been lost. Still, the forests of southeastern North America are disappearing at an alarming rate. Despite comprising only 2% of the world's forest cover, the southern forests are being harvested to supply 12% of the world's wood products. This is simply not sustainable. If nothing is done to slow this progress, the world stands to lose yet another biodiversity hotspot. 

If this sounds as bad to you as it does to me then you probably want to do something. Please check out what organizations such as The Longleaf Alliance, Partnership For Southern Forestland Conservation, The Nature Conservancy, and The National Wildlife Federation are doing to protect this amazing region. Simply click the name of the organization to find out more.

Further Reading: [1] [2] [3] [4] 

Giant Trees Discovered in Africa

[SOURCE]

As far as tall trees are concerned, Africa has long been excluded from the list... until now. During a recent botanical survey of Mt. Kilimanjaro, a research team located a stand of large trees tucked away in a remote valley. Some of these trees were giants.

Tall trees are the result of a perfect storm of evolutionary history and unique environmental conditions. From the redwoods of the Pacific Coast to the Eucalyptus of Tasmania, rich soils, low levels of disturbance, and competition for light have driven some species to grow to mind boggling proportions. It seems fitting then that Africa's tallest mountain was hiding its tallest trees all this time. 

The species in question is known scientifically as Entandrophragma excelsum and belongs to the mahogany family (Meliaceae). A total of 13 giant E. excelsum were found during this expedition. Heights ranged from a modest 53.7 meters (176 ft) to a staggering 81.5 meters (267) in height! Unlike other species in this "Tall Tree Club," E. excelsum produces wood of surprisingly low density. However, it is thought that this low density wood, which is much less costly to produce, allows the trees to grow quick enough to avoid being overrun by vines before it can make it to the canopy. Indeed, very few E. excelsum were found to have vines growing on them. 

Although these are nowhere near the tallest trees in the world, they nonetheless break the African tall tree record, which was previously held by a non native Eucalyptus that died in 2006. The reason these African giants were not found sooner has to do with the remote region in which they grow. The area around Mt. Kilimanjaro has not received much attention from botanists in the past, having been overshadowed by the biodiverse Eastern Arc Mountains further south. 

Aside from discovering these trees, botanical surveys of Mt. Kilimanjaro are revealing this region to be just as biodiverse as the Eastern Arcs. Sadly, because of its long history of agriculture and more recent history of illegal logging, the rich forests of Mt. Kilimanjaro are quickly disappearing. The research team stresses the need to protect this area before one of Africa's biodiversity hotspots, as well as its tallest trees, are lost forever. 

Further Reading: [1]

Ancient Saw Palmettos in the Heart of Florida

When we think about long lived plants, our minds tend to fixate on bristlecone pines (Pinus longaeva), coastal redwoods (Sequoia sempervirens), or that clonal patch of quaking aspen (Populus tremuloides) in Utah. What would you say if I told you that we can add a palm tree to that list? Indeed, recent evidence suggests that the saw palmetto (Serenoa repens) can reach a ripe old age measured in thousands (yes, thousands) of years.

Now, at this point some of you are probably thinking "how can you measure the age of a palm when there are no annual growth rings?!" This is a legitimate hurdle that had to be overcome before such a claim was made. Using a lot of attention to detail and some crafty mathematics, a team of researchers was able to age saw palmettos in Florida's most ancient habitats.

This work was performed on a peculiar geological formation. Aptly named the "Mid-Florida Ridge," this 150 mile sand ridge bisects the middle of the state. Throughout much of the Pliocene and early Pleistocene, sea levels were as much as 50 meters higher than they were today. Nearly all of Florida was underwater during this time. All that stuck out above the water were a series of small islands. These islands served as refugia for flora and fauna as sea levels changed and repeated glaciations forced species south. Once the ocean receded to its current level, these islands were left high and dry, thus forming the ridge in question. Because of its history as a refugium, the Mid-Florida Ridge is home to a staggering array of plant species, some of which are endemic to this small area of the continent.

Because of its relative stability through time, the Mid-Florida Ridge is a haven for long lived plant species. Thus, it was a prime location for trying to understand the longevity of the charismatic and ecologically important saw palmetto. By tagging individual palms and observing them year after year, researchers were able to get an idea of exactly how fast this species can grow. Depending on soil conditions, saw palmettos grow at a rate of somewhere between 0.88 and 2.2 cm per year. They certainly aren't winning any speed races at that rate. Regardless, you can begin to see that an estimate of yearly growth rate can shine a light on how long these palms have been around. Measurements of tagged palmettos growing on the sand ridge show that individuals aged at a staggering 500 years are not uncommon!

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The light sandy looking area in the middle is the Mid-Florida Ridge. Map vis USGS Public Domain.

This estimate gets a bit complicated when we consider another aspect of saw palmetto biology - they are clonal. For a variety of reasons, as saw palmettos grow, their sprawling stem will often branch out, creating clones of themselves. Over time, the trunk portions that connect these clones rot away, giving the impression that they are unique individuals. Genetic analyses showed that many of the palmettos in the study area were actually clones. Using some pretty sophisticated models coupled with DNA evidence, the research team was able to reconstruct the growth history of many of these clones, thus allowing them to more accurately age these clonal colonies.

Their results are staggering to say the least. Based on the rate of growth and spread, the estimated age of these clonal patches of saw palmetto range anywhere between 1227–5215 years! At this point you should be asking yourself "how accurate are these data?" The truth is that the researchers were actually being quite conservative in their estimates. For instance, there were likely many clones well outside their study area. If so, they were likely underestimating the growth time of these clonal colonies. Additionally, they were only using the growth rates of adult saw palmettos in calculating average growth rates.

Seedling saw palmettos have been shown to have a reduced growth rate compared to adults, only 0.3 cm per year. Thus, they did not take into account the time it takes for seedlings to reach maturity. The team feel that accounting for such variables could increase the age estimates for such clonal patches to well over 8,000 years! I don't think we should be looking into buying that many birthday candles just yet, however, even their reported estimates are shocking to say the least.

Partially exposed trunks following a prescribed burn.

What we can say is that for as long as Florida has been above water, saw palmettos have played an integral role in the ecology of the region. The saw palmetto has shaped these sand ridge communities into the ecosystems they are today. It is without a doubt, a species worthy of our admiration and respect.

Photo Credits: [1]

Further Reading: [1]

Tomatillos Just Got A Lot Older

Photo by Ignacio Escapa, Museo Paleontológico Egidio Feruglio

Tomatillos and ground cherries just got a bit older. Okay, a lot older. Exquisitely preserved fossils from an ancient lake bed in Argentina are shining a very bright light on the genus Physalis and the family Solanaceae as a whole. Despite the importance of this plant family around the globe, little fossil evidence has ever been found. That is, until now. 

Dated at 52 million years old, these fossils paint a picture of a snapshot in the evolution of the genus Physalis. The fossils are remarkable, allowing for close inspection of minute details like vein structure. Because of the level of detail discernible, experts can say without a doubt that these fossils could be nothing else other than a species of Physalis. 

One of the most interesting aspects of these fossils is their age. These sediments were deposited during the early Eocene Epoch. The fact that representatives of Physalis were alive and well during this time is quite remarkable. Because fossil evidence for Solanaceae has been so scarce, experts have had to rely solely on molecular dating in order to elucidate the origin and divergence of this family. 

Original estimates placed the origin of Solanaceae at sometime around 30 million years before present. Physalis, being much more derived, was thought to have an even more recent emergence, some 9 million years ago. Boy, was that ever wrong. At 52 million years of age, we can now confidently say that Physalis is at least 43 million years older than previously thought. These findings also tell us that Solanaceae is even older still! If such a derived genus was thriving in Eocene Argentina 52 million years ago, basil members of the family must have gotten their start much earlier than we ever imagined. 

Aside from big picture taxonomical revelations, the fossils also give us a window into the ecology of these ancient Physalis. The most obvious is that inflated bladder which surrounds the berry within. Though it is quite characteristic of this group, little attention has been paid to its function. The fact that the sediments in which they were preserved are of aquatic origin suggests that the inflated calyces may have evolved for aquatic seed dispersal. Experiments have shown that these structures on modern day ground cherries and tomatillos do in fact float, keeping the berry inside high and dry. 

To think that all of this was brought to light from a handful of fossils. It just goes to show you the importance the paleontological discoveries can have. Just think of the countless amount of museum drawers and shelves that are chock full of interesting fossils waiting to be looked over. Who knows what they might tell us about our planet. 

Photo Credit: Ignacio Escapa, Museo Paleontológico Egidio Feruglio

Further Reading: [1]

Mayaca!

When I first saw this little plant growing along the boarders of a pond, I thought I was seeing a semiaquatic Lycopod. Was I ever wrong. It turns out I was looking at an angiosperm commonly encountered by aquarium enthusiasts - Mayaca fluviatilis. The genus Mayaca has its own family (Mayacaceae) and its members can be found throughout Southeastern North America, Latin America, the West Indies, and central Africa. It was very exciting to meet one of these plants in person!

Pseudoanthry

I learned a new word today - "pseudoanthery." This term applies to a structure or organ on a nectarless flower that mimics a dehiscent anther. To elaborate further, a dehiscent anther is one in which a capsule containing pollen breaks open to reveal the pollen inside. For example, think of the anthers of an Asiatic lily. Back to the topic at hand.

I quite like learning new things, especially as it applies to familiar friends. I was admiring the floral display of a rather tall cane begonia when a friend of mine came up to me and simply said "pseudoanthery." I didn't quite catch it the first time so I asked him to repeat it. It wasn't hard to guess the root meaning of the word - fake anther. Confusion set in when I pointed out that I was looking at the female flowers of a begonia. Thus, a teaching moment presented itself.

Though I adore Begonias and have a small handful growing in my house at all times, I never stopped to think much about their pollination. Without a doubt, they can be quite showy. Even the smaller species can put on quite a floral show. Rarely have I ever detected a scent from a Begonia bloom, nor have I ever detected nectar (though that's not to say either of those qualities don't exist). The point I am trying to make is that I couldn't quite figure out their strategy.

Sure, male flowers contain copious amounts of pollen. That is incentive enough to visit a male bloom. But what about the female flowers? Do they get away with not offering any sort of reward by simply being showy? Certainly that helps, however, female Begonia flowers sweeten the ruse with a bit of mimicry.

That is where the term pseudoanthery applies. Take a close look at the stigma of a begonia flower and you will be marveled by its intricate structure and bright coloration. As it turns out, the stigma is shaped in such a way as to mimic the pollen covered anthers of male flowers. Insects looking for protein rich pollen with visit the female flowers, realize it was all for naught, and move on. That is all the female flowers require. While the insect was busy searching for pollen, it is very likely that the bristly hairs on the stigma were able to pick up pollen grains from the insect's previous visit. With a little luck, that flower was a male begonia.

This ruse works best at large numbers. By producing lots of male flowers and considerably fewer female flowers, Begonias can ensure that the insects are not deterred by the lack of rewards. This has a double benefit for the plant as female flowers and seeds can be costly to produce.

Quite fascinating if I do say so myself. I have looked at countless Begonia flowers and not once did I question their structure. Just goes to show you that even old friends can teach us new things.

Further Reading: [1] [2]

A Peculiar Case of Bird Pollination

Via Johnson and Brown [SOURCE]

When we think of bird pollination, we often conjure images of a hummingbird sipping nectar from a long, tubular, red flower. Certainly the selection pressures brought about from entering into a pollination syndrome with birds has led to convergence in floral morphology across a wide array of different plant genera. Still, just when we think we have the natural world figured out, something new is discovered that adds more complexity into the mix. Nowhere is this more apparent than the peculiar relationship between an orchid and a bird native to South Africa.

The orchid in question is known scientifically as Disa chrysostachya. It is a bit of a black sheep of the genus. Whereas most Disa orchids produce a few large, showy flowers, this species produces a spike that is densely packed with minute flowers. They range from orange to red and, like most other bird pollinated flowers, produce no scent. 

Take the time to observe them in the field and you may notice that the malachite sunbird is a frequent visitor. The sunbirds perch themselves firmly on the spike and probe the shallow nectar spurs on each flower. At this point you may be thinking that the pollen sacs, or pollinia, of the orchid are affixed to the beak of the bird but, alas, you would be wrong. 

Closer inspection of the flowers reveal that the morphology and positioning of the pollinia are such that they simply cannot attach to the beak of the bird. The same goes for any potential insect visitors. The plant seems to have assured that only something quite specific can pick up the pollen. To see what is really going on, you would have to take a look at the sunbird's feet. 

That's right, feet. When a sunbird feeds at the flowers of D. chrysostachya, its feet position themselves onto the stiffened lower portion of the flower. This is the perfect spot to come into contact with the sticky pollinia. As the bird feeds, they pick up the pollinia on their claws! The next time the bird lands to feed, it will inevitably deposit that pollen. The orchids seemed to have benefited from the fact that once perched, sunbirds don't often reposition themselves on the flower spike. In this way, self pollination is minimized. A close relative, D. satyriopsis, has also appeared to enter into a pollination with sunbirds in a similar way. 

Though it may seem inefficient, research has shown that this pollination mechanism is quite successful for the orchid.The pollinia themselves stick quite strongly so that no amount of scuffing on branches or preening with beaks can dislodge them. Once pollination has been achieved, each flower is capable of producing thousands upon thousands of seeds.

Photo Credit: Johnson and Brown

Further Reading: [1]