These plants comprise 4 species, all of which exhibit to some degree or another features we tend to associate more with animals than with plants. On the almost two dozen life-bearing worlds visited by Humankind, the division between plant and animal is clear, at least beyond the level of one-celled creatures. On Amaterasu, the line is clearly drawn, as well, for all species except those of the motile plants.
It is tempting to view these 4 species as steps along an evolutionary trail from least complex to most, but there is insufficient data to trace an evolutionary connection with any certainty. The notion of "more complex" and "least complex" is confused, as well, since even organisms with less complicated structures can contain sophisticated internal mecahnisms. We will consider these plants according to a "complexity" scale, but this is merely heuristic: we imply thereby no assertion that one type evolved from the other.
The first type of motile plant to be considered has been named the Rossette Plant by Human researchers. It resembles the terrestrial succulent species Sempervivum (houseleek) and presents itself as a low-growing cluster of thick, dark green, wedge-shaped leaves about 12 cm in diameter. Underground is a bulbous root about the size of a softball. In the center of the rossette is an whorl of leaves of finer structure, which can iris open with surprising speed to reveal the digestive cavity contained in the tuberous root. Ringing the central whorl are tiny purple eyebuds, little structures like unopened flower buds which are sensitive to light. The plant extends a network of fine fronds like fern stalks along the ground to a distance of about a meter all around.
When an animal of appropriate size happens across the network of extended fronds, those fronds beneath it are triggered to wrap around the creature's legs and body. Some varieties of Rossette Plant exude a scent to attract their prey. Once the prey has been encased in fronds, the stem retracts to the plant, dragging the prey with it. The plant eventually pulls the captured prey over the central whorl. There, the eyebuds size up the prey, and animals too large to be engulfed are released. The unfortunate others are deposited within the digestive cavity, the central whorl irises shut, and the plant digests its meal. The capture process can take several hours, and complete digestion can take a week or more.
When the Rossette Plant commences its reproductive cycle, it first grows a tall multi-branched stalk from the center. Tiny white flowers appear on the branches of the stalk and are pollinated by flying insects. These flowers develop into small pods of mottled yellow-green about the size of an almond, with two extended wings like the blades of a maple seed. As the seeds mature, these wings begin to flap, the stem holding the seed to the stalk dries up and becomes brittle, and eventually the seed pod tears itself away from the flower stalk and flies off. These flights appear totally random and erratic, and last no more than 5 to 10 minutes, but they serve to disperse the plant's seed over a considerable area. Once the seedpod's energy is exhausted, the pods fall to the ground, there to germinate and begin the cycle again.
The second species to be considered is much larger, and its leaves are thinner, but much larger than those of the Rossette Plant. It somewhat resembles the terrestrial agave, from which it takes its name of Bird Agave. In this species, the plant itself is entirely conventional in nature; the carnivorous and flying apparatus have all been moved from the plant to the seedpod itself. When the Bird Agave is ready to reproduce, it also grows a flower stalk appropriate to its size, and its flowers are pollinated in the usual way. Seedpods about the size and color of an okra pod develop from the flowers. These pods have much larger main wings, and they also have small leaves centered around the stem end. At the blossom end are a mouth in the form of a whorl of leaves, and an eyeband like a tiny strip of reddish moss across the "forehead", comprised of dozens of tiny eyepits.
As with the Rossette Plants, the seedpods of the Bird Agave become active as the pods mature, and eventually break free. But they are capable of much longer flights, and their rear leaf structures provide a sort of "tail", allowing them much greater control of their flight. They use their eyebands to seek and capture tiny flying insects, which they scoop into the whorl of their mouthleaves, which is opened wide like a funnel during flight. The pods usually break free at sunup and continue in flight all day long, but when nighttime comes, their eyebands are inadequate for sight, and they cease their hunting. As their energy runs out, their wings beat more slowly. Since they have no feet, they cannot light somewhere, but simply crash to the ground as evening deepens. But their daylong flight has served to disperse their seed over a distance of a kilometer or more in the swampy, treeless regions where they flourish.
A close cousin is the Spider Agave, as the name implies. This plant is found in the drier uplands of Amaterasu. Its leaves resemble those of the Bird Agave, being only slightly broader and less spiny. But it does not form a stalk when it flowers, rather, large yellow flowers grow from the base, and it does not produce a flying pod, but a seedpod with legs. When mature, these seedpods are about 6 cm in diameter and resemble tiny patty pan squashes, decorated with splashes of white, yellow and brown. They have five lobes, with one leg on each. The legs are jointed like those of an insect. Between each lobe is an eyestrip that extends beneath the pod, where the mouth is located (at the blossom end). These hunt their prey primarily by standing in one place and dropping down onto anything suitable that runs beneath them. They have a much longer lifespan than the flying pods, typically up to a month, and can travel much greater distances. In time, they too run out of energy, sink to the ground, and germinate.
Both Agave species produce seedpods in prodigious amounts, since both are a favorite food of many plant-eaters in the regions in which they are found. If they did not produce so many seeds, there would hardly be enough left to propagate the species. One can speculate that one reason for the evolution of meat-eating in this species was to provide this vast amount of seed with the food resources needed for growth, the need for which would quickly exhaust any parent plant that tried to provide them by itself.
The most sophisticated of the motile plants is the tykva (Russian for pumpkin). This creature undergoes a two-stage lifestyle, at the end of which it is a fully independent creature with capabilities little different from an animal. It begins life as a small plant much like the Rossette Plant, but rapidly grows a central globe structure. While the seasons are not pronounced on Amaterasu, there are areas in the upper latitudes which do experience noticable variations in temperature and humidity, and the tykva inhabits these regions. It grows during the summer, and by fall, resembles an enormous yellow kohl-rabi plant, with a central bulb the size of a melon surrounded by large flat green leaves on thick yellow stalks. As the fall progresses, the leaves dry up and fall off, leaving an orange ball with thick rind on the forest floor. Throughout the winter, this rind dries and thins, and by spring, when the plant life comes out of dormancy, it is no more than a paper-thin shell. This shell the tykva breaks open to begin the next phase of its life.
The motile phase of the tykva resembles a flattened, five-lobed patty pan squash about 20 cm in diameter, decorated in mottled yellow, green and orange. Internally, it possesses muscles activated by hydraulic pressure changes and a nervous system the equal of simple insects. It has jointed legs and eyestrips between its lobes and a mouth on the underside, like the Spider Agave. But it also has tendrils ringing its mouth. It is no passive lurker, but it actively seeks its prey, running it down and grabbing it with its tendrils. Interestingly, it seems to have no preferred orientation, that is, if it walking in one direction and wants to change direction, it does not turn its body, but simply begins moving in the desired direction. This evidently is quite unnerving to its prey, for it is a very successful hunter despite being capable of only brief bursts of speed.
Once a season, when it enters the reproductive cycle, the tykva grows a stalk from its back, but the stalk does not have flowers, just simple green "pitchers" on the ends. It must seek out a mate, also in flower, and they pollinate each other by rubbing the stalks together. Once the seeds develop, the tykva's method of distribution is simple in the extreme: as the seeds mature, the stalk dries and grows brittle, and the seeds simply break off and fall to the ground during its travels.
The tykva lives for several seasons, wintering over by finding a sheltered spot to wedge into and going dormant. It has no fixed range, but wanders freely over its entire habitat. It can cover several hundred kilometers throughout its lifetime. Tykva are solitary, but are not aggressive to each other; indeed, they hardly seem aware of each other except at pollination time. They have few natural enemies except for some large foraging species; the tykva contain a natural alkaloid that makes them unpalatable to other plant-eaters.
These 4 plant species are a fascinating tribute to Nature's capacity for invention. It is hoped that current attempts to cultivate these on Earth will allow many others to see and appreciate these unique specimens.
© 1997, Terrence Donnelly