Coontail is a perennial plant growing beneath the water surface. Plants
produce only one branch per node. They lack roots but branches are sometimes
modified as "rhizoids" giving the plants a rooted appearance.
The leaves are sessile, whorled, ca. 3 cm long, 5 or more at a node, rigid
and often brittle. The leaves are 1-2 (sometimes 3) times forked into
2-4 filiform or linear segments. Minute teeth occur along 1 margin of
each ultimate segment. The flowers are unisexual, very small, solitary
in the axil of a leaf of a given whorl, each subtended by an 8-10 parted,
1-2-mm-long involucre. Sepals and petals are absent. The fruit is one-seeded
with a spiny base.
Coontail grows in rivers, streams, lakes, lagoons and irrigation ditches
throughout temperate North America. It is tolerant to fluctuating water
levels and high turbidity. Stems break easily and pieces continue to grow
separately. The fruits are probably dispersed by animals and by water.
Large populations restrict navigation and recreational water use. C.
demersum has the ability to grow in areas unsuitable for other aquatic
species. These plants are sometimes the dominantones in a given habitat,
crowding out other species.