Wicked Waterwhip

Non-photosynthetic centipedeweeds known as stranglesnares, which have evolved into true carnivores thanks to genes acquired from fungal symbiotes and so lost their capacity to gain energy from sunlight, are now widespread in the expansive caves that underly Serinarcta. Yet as derived as those plants are - they were once simple grasses, recall - these are not the current extreme of their evolutionary lineage. There are, in fact, species related to them which are even more divergent from their ancestors. Those plants are the woodwhips - a subgroup of stranglesnares which have escaped the caves once more, and returned to a life in the sunlit world, forever changed by their time spent in the dark. 

Woodwhips evolved from stranglesnares around 3 million years ago. They are the descendants of seeds released by cave-dwelling parents which failed to catch onto a suitable cave rock during flooding, or to be carried on the fur of some cave animal, and which instead were floated out of the caves entirely, either through groundwater rivers ultimately leading to water bodies like the Centralian sea, or through inundation events where the polar basin overflowed, filling northern caves to their brim and overflowing groundwater across the upperglades (the precise origin of these plants may well be from both places.) Taking root on shoreline rocks or dark places on the swampy forest floor, these plants could survive here as well as underground, and retained their predatory nature, allowing them to find nourishment even in long polar winters when other plants became dormant. And from the woodwhips then came the waterwhips, specialized forms of these plants adapted to float on floodwaters indefinitely, rather than to take root on some tree or stone. 

While other centipedeweeds attach themselves to a surface with powerful clamping roots and there remain for the rest of their lives, the waterwhips have evolved a large, hollow chamber in their stolons (the stems from which their leaves and roots originate) filled with air, which lets them drift along upside-down at the water surface. They travel with currents to wherever nutrients suspended in the water are also carried - normally, meaning it is always kept floating in environments with a higher density of prey than surrounding areas. The waterwhip still grows roots, and though they serve some use to collect dissolved nutrients from the water, they are harmless to animals like fish and insects, and form a protective shelter in the water to which such animals are attracted. These roots hide the deadly tendrils, the predatory razor-sharp leaves common to all centipedeweeds, on which they sometimes become snared by the thousands of small, sharp hooks made of silica. A small animal trapped on these fishing lines causes them to wrap up and coil, further ensnaring the victim, which is gradually lifted to the crown of the plant and tightly enveloped into an expanding pouch at the base of all its leaves, where digestive enzymes dissolve it and make short work of the hapless creature.

Though waterwhips have long since lost lost the genes necessary to produce their own chlorophyll and photosynthesize, living in the sun as they now do once again, they have adapted in an entirely new way to make use of the light that surrounds them. Their gas bladder, being comprised of a thin, fleshy membrane, is an ideal habitat for microscopic dinoflagellate algae to thrive, sheltered from their predators. As they photosynthesize in this protected microcosm, they share a portion of the sugars they produce with their host plant, making it both an autotroph (a producer of energy) and a heterotroph (a consumer of it.) Yet unlike their ancestors, which were green plants, waterwhips are always a dirty brown color, for their host algae is not a green algae, and uses different pigments for photosynthesis. This has the added benefit of protecting the plant from herbivores seeking nutritious green food, which find it unappetizing and usually mistake it to be dead. This is all the better, because its dinoflagellate symbiotes produce neurotoxins when their cells die, which are accumulated in the tissue of their host plant for defense, providing it protection from herbivores even during the polar winter when little else is available to eat. The wicked waterweed, endemic to the polar basin, is one of the only plants that can remain growing throughout the long dark winter.

Waterwhips reproduce mainly through clonal division, producing offshoots called "pups" that attach via a stolon to the parent until they are big enough to detach and float away on their own. They are capable of flowering and setting seed, however, and when they do so, their seeds are carried away in the water to a shoreline setting where they initially require a hard surface on which to take root. Unlike pups produced by mature plants, seedlings take up to three years to be large enough to detach from their holdfasts and become aquatic.