The Grab-Basket and the Pitcher Palm: Killer Plants of East Ailuropia

Pitcher Palms (Carnivorodendron) are mid-sized palm-grasses basal to both pocketwoods and palmsnaps. Like palmsnaps, they have no specific adaptations for preserving their structural integrity at large sizes, so their main trunk does not exceed 10 meters tall and 75 centimeters wide. Their branches are slender and flexible, rarely growing woody tissue at all. This gives pitcher palms the appearance of a slender stick topped with dozens of noodly shoots. At the end of each of these stems is the plant's killing apparatus. The phytotelmata within this grass's leaf axils are death traps for small organisms, as the blades are smooth and slippery, preventing anything that falls in from escaping. This initially evolved to deter plant-eating mosquitoes from attacking its foliage, but it has since become a useful source of supplemental trace elements. Curiously, unlike many carnivorous plants, this genus does not produce nectar or any other bait to attract its victims. Instead, it relies on its entourage of isopods to do its dirty work. 

Like most palm-grasses, the pitcher palm harbors multiple species of symbiotes, and one of these is found on no other tree. The Plague Doctor (Pestiloraptor agnathus) is a large snatcher woodlouse that takes an active approach in ridding its territory of plague. Individuals leave their home tree frequently, seeking out Pestilarthrids as far as half a kilometer away. However, they don't eat their prey; in fact, they've lost their chewing mouthparts entirely in exchange for a short nectar-lapping proboscis. When they arrive back at the palm-grass, they find an axil and deposit their catch. Like many Scansoriarthriforms, plague doctors can survive on the tree's extrafloral nectar alone. Another trait they share with their relatives is that, at any given time, a small fraction of their population consists of freeloaders who do no work to protect their host tree. These moochers don't branch off into their own species or subspecies, as doing so would negate their main advantage: they look and smell identical to their more helpful cousins (a word used literally in this instance). As long as their numbers remain only a small fraction of the total population, they can remain under the radar. Their conspecifics never evolve to detect their parasitic ways, and the tree loses only an insignificant amount of nectar.

Growing low to the ground in the same forests as the pitcher palm is another plant with a very different means of catching its prey. The Grab-Basket (Podocisor subfolium) is a descendant of the can-grass; in fact, its genus is sister to the less specialized pitcher-baskets that inhabit sunny wetlands where nitrogen is the only limiting factor in growth. Podocisor, on the other hand, became isolated in closed forests with little access to the direct sunlight they were adapted to. Plants in these conditions usually either die off or evolve to grow on little solar energy, but the grab-basket has found a new way to survive. Its blades grow horizontally on the forest floor, their downturned tips pushing under fallen leaves. Though this hinders photosynthesis, it allows the basket-grass to camouflage perfectly, remaining hidden as it spreads up to 30 centimeters in width. When a small animal trods upon the plant, it triggers an explosive burst of energy down the length of each blade. Their upper surfaces contract in a fraction of a second, trapping their prey in a spherical prison that continues shrinking by the second. In less than a minute, there are no more gaps between the blades. The digestion process is slow, as the plant has no dedicated digestive enzymes. The best it can do is wrap tightly around its victim, secrete some acidic secondary metabolites, and wait for bacteria to do the dirty work of breaking the carcass down into a slurry of biological matter that can be absorbed through the blades. The exposed abaxial leaf surfaces are thorny and tough, preventing scavengers from stealing the grab-basket's kill. The plant, having thrown off its covering of leaf litter, is finally able to photosynthesize at this stage, but its meal contains more energy than it could hope to glean from the scant sunlight that reaches the ground. The grab-basket is the only carnivorous plant that gains most of its calories from its prey rather than the sun. In fact, it doesn't even need animals for nitrogen or other nutrients, for the soils of this forest contain more than enough on their own. Thus, this species occupies a niche more like that of an animal ambush predator than a typical carnivorous plant.