Something Strange in Mexico

lac2.JPG

I assure you that what you are looking at here is indeed a plant. I would like you to meet the peculiar Lacandonia schismatica, one of roughly 55 species belonging to the family Triuridaceae. Not a single member of this family bothers with leaves or even chlorphyll. Instead, all members are mycoheterotrophic, meaning they make their living by parasitizing fungi in the soil. However, that is not why L. schismatica is so strange. Before we get to that, however, it is worth getting to know this plant a little bit better.

The sole member of its genus, Lacandonia schismatica grows in only a few locations in the Lancandon Jungle of southeastern Mexico. Its populations are quite localized and are under threat by encroaching agricultural development. Genetic analyses of the handful of known populations revealed that there is almost no genetic diversity to speak of among the individuals of this species. All in all, these factors have landed this tiny parasite on the endangered species list.

Mature flower of  Lacandonia schismatica . Three yellowish anthers (center) surrounded by rings of red carpels. Scale bar = 0.5cm.”  [SOURCE]

Mature flower of Lacandonia schismatica. Three yellowish anthers (center) surrounded by rings of red carpels. Scale bar = 0.5cm.” [SOURCE]

To figure out why L. schismatica is so peculiar, you have to take a closer look at its flowers. If you knew what to look for, you would soon realize that L. schismatica appear to be doing things in reverse. To the best of our knowledge, L. schismatica is the only plant in the world that known to have an inverted flower arrangement. The anthers of this species are clustered in the center of the flower surrounded by a ring of 60 or so pistils. The flowers are cleistogamous, which means they are fertilized before they even open, hence the lack of genetic diversity among individuals. 

Not all of its flowers take on this appearance. Researchers have found that in any given population, a handful of unisexual flowers will sometimes be produced. Even the bisexual flowers themselves seem to exhibit at least some variation in the amount of sexual organs present. Still, when bisexual flowers are produced, they only ever exhibit this odd inverted arrangement.

lac1.JPG

It is not quite clear how this system could have evolved in this species. Indeed, this unique floral morphology has made this species very hard to classify. Genetic analysis suggests a relation to the mycoheterotrphic family Triuridaceae. It was discovered that every once in a while, a closely related species known as Triuris brevistylis will sometimes produce flowers with a similar inverted morphology.

This suggests that the inversion evolved before the Lacandonia schismatica lineage diverged. One can only speculate at this point. The future of this species is quite uncertain. Climate change and habitat destruction could permanently alter the conditions so that this plant can no longer exist in the wild. This is further complicated by the fact that this species has proven to be quite difficult to cultivate. Only time will tell. For now, more research is needed on this peculiar plant.

Photo Credit: [1] [2] [3]

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

Caliochory - A Freshly Coined Form of Seed Dispersal

Turdus_merula_nest.jpg

A new form of seed dispersal has been described. It involves birds but not in the sense we traditionally think. Everyone understands how effectively birds disperse seeds contained in small fruits such as berries, or as barbs attached to their feathers. It took finding an out-of-place patch of Japanese stiltgrass (Microstegium vimineum) for lead author Dr. Robert Warren to start looking at bird dispersal in a different light. 

While working in his yard, he noticed a patch of Japanese stiltgrass growing out of a window planter some 6 feet off the ground. Japanese stiltgrass can be highly invasive but its seeds aren't adapted for vertical dispersal. However, it does employ a mixed mating system composed of outcrossing flowers at the tips of the spikes along with cleistogamous flowers whose seeds remain on the stem. Taking out a ladder, Warren discovered that the grass was growing out of a bird nest. It would appear that stiltgrass stems containing seeds were incorporated into the nest as building material and then germinated the following year. Thus began a deeper investigation into the realm of nest seeds.

Teaming up with researchers at Yale and the United States Forest Service, they set out to determine how often seeds are contained within bird nests. They collected nests from 23 different bird species and spread them over seed trays. After ruling out seeds from potential contamination sources (feces, wind, etc.), they irrigated the nests to see what would germinate. The results are quite remarkable to say the least.

Over 2,000 plants, hailing from 37 plant families successfully germinated. In total, 144 different plant species grew from these germination trials. The seeds appeared to be coming in from the various plant materials as well as the mud used to build these nests. What's more, nearly half of the seeds they found came from cleistogamous sources. Birds whose nests contained the highest amounts of seeds were the American robbin (Turdus migratorius) and the eastern bluebird (Sialia sialis). These results have led the authors to coin the term "caliochory," 'calio' being Greek for nest and 'chory' being Greek for spread.

It has long been assumed that cleistogamous reproduction kept seeds in the immediate area of the parent plant. This evidence suggests that it might actually be farther reaching than we presumed. What's more, these numbers certainly hint that this otherwise unreported method of seed dispersal may be far more common than we ever realized. Whether or not plants have evolved in response to such dispersal methods remains to be tested. Still, considering the diversity of birds, their nesting habits, and the availability of various plant materials, these findings are quite remarkable!

Photo Credits: [1]

Further Reading: [1]

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

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

The discovery of this species is quite exciting. The flora of Japan has long thought to be well picked over by botanists and ecologists alike. Finding something new is a special event. The discovery was made by Suetsugu Kenji, associate professor at the Kobe University Graduate School of Science. This discovery was made about a year after a previous parasitic plant discovery made on another Japanese island a mere stones throw from Kuroshima (http://bit.ly/2dYN12L).

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

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

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

Photo Credit: Suetsugu Kenji

Further Reading:

[1]