This is a submerged or floating aquatic plant (about ½–12' long)
that branches at right angles (90°). The jointed stems are
pale green to reddish purple,
glabrous, and fragile, often dividing into smaller segments. Along
these stems, there are whorls of 5-14 divided leaves that curve upward;
these leaves are 1-4 cm. long. The leaves are more crowded toward the
growing tips of stems than elsewhere; they are
medium to dark green and glabrous. Both stems and leaves have a
tendency to be somewhat stiff and brittle, especially when they are
coated with lime in calcareous water. Each leaf divides dichotomously
into 2-4 segments (rarely more); these segments are narrowly linear (up
to 0.5 mm. across) and flattened. Each leaf segment is conspicuously
toothed along one side, while it is smooth (entire) on the other side.
Coontail is monoecious, forming male (staminate) and female
(pistillate) flowers on the same plant. Both types of flowers are
produced in the axils of the leaves and they are sessile. Female
flowers occur individually, while male flowers occur either
individually or in pairs. Both types of flowers are very small in size
(about 2 mm. in length), and they have involucres consisting
of 8-14 floral bracts that surround the reproductive organs.
These bracts are translucent and broadly oblong; their tips are
truncate and fringed. There are neither sepals nor petals. Each female
flower has a single pistil with a long slender style, while each male
flower has 8-14 anthers that are sessile or nearly so (very short
or absent filaments). The blooming period occurs intermittently during
the summer and early autumn. Cross-pollination is accomplished through
water currents. However, only a few flowers, if any, are produced by
individual plants. The female flowers are replaced by 3-spined achenes.
The body of each mature achene is 4-6 mm. long, ovoid in shape,
slightly flattened, and wingless along its sides. Each achene has 2
basal spines and a single spine at its apex; these spines are 0.5-12.0
mm. in length and they are either straight or curved. Coontail has no
real root system, although it is able to anchor itself in mud or sand
through either lodged stems or the development of modified leaves. By
late autumn, winter turions (tight buds of leaves) develop at the tips
of stems that sink to the bottom of a body of water, where they
remain until spring of the following year. Growth and development begin
again with the return of warmer weather. In addition to its achenes and
winter turions, Coontail reproduces vegetatively whenever its stems
divide into smaller segments.
The preference is full sun and relatively clear water up to 9'
deep that has adequate levels of nutrients; water pH can be mildly
acidic to alkaline. At the water's bottom, the soil should consist of
mud, sandy mud, or muddy gravel. Coontail is more tolerant of
shade than the
majority of aquatic plants and it is able to tolerate some turbidity in
the water if it is not excessive. This aquatic plant can adapt to sites
with either stagnant water or slow-moving currents where there is some
protection from wind and waves. Because of its phytotoxic properties,
Coontail can inhibit the growth of phytoplankton and
blue-green algae (cyanobacteria). At some locations, it can spread
aggressively and become a pest.
Coontail is occasional to common throughout Illinois. This species is
native to a wide area of North America, from where it has
spread to other parts of the world. Habitats include quiet inlets of
lakes, ponds, rivers with
slow-moving currents, marshes, and springs. Generally, Coontail is
typically found in bodies of water with muddy bottoms, although it also
occurs where the water bottom contains some sand or rocky material.
Sometimes Coontail is cultivated as an aquarium plant. It has also been
introduced deliberately into polluted bodies of water in bioremediation
projects because of its ability to absorb suspended particles of
chromium, lead, arsenic, and other chemicals.
The leaves of Coontail provide hiding places
aquatic organisms and its leaves are sometimes grazed by snails. Both
the foliage and seeds of this aquatic plant are eaten by the American
Coot (Fulica americana
species of waterfowl (see the Waterfowl Table
and some turtles (Legler, 1943;
Ernst et al., 1994), including the Musk Turtle (Sternotherus
), Snapping Turtle (Chelydra serpentina
Blanding's Turtle (Emys
), Painted Turtle (Chrysemys picta
River Cooter (Pseudemys
), and Slider (Trachemys
). This aquatic plant is also
eaten by carp and, to a lesser extent, by muskrats. The foliage and
seeds of Coontail can spread to new wetlands through human activity.
For example, when people dump the content of aquariums into waterways
that contain Coontail, it can easily establish itself in such habitats.
Similarly, because Coontail can cling to anchors, boat trailers,
fishing nets, and
dredging equipment, it may be transported considerable distances from
one body water to another.
In shallow water of a sandy marsh at the Heron
Vermilion County, Illinois.
Coontail superficially resembles some Chara spp.
latter are actually algae, rather than vascular plants. Coontail can be
distinguished by its leaf segments, which have teeth along only one of
2 sides (rather than both), and its crushed foliage lacks the
distinctive garlic or skunk-like smell that is so typical of many Chara
. A closely related species, Ceratophyllum echinatum
Hornwort), is also found in Illinois, but it is less common. Compared
to Coontail, Spiny Hornwort has softer foliage and its leaf segments
either lack teeth or they have less conspicuous teeth along one side of
their leaf segments. In addition, the achenes of Spiny Hornwort are
shallowly winged along their sides, and each winged side of an achene
has 3-10 spiny teeth. Although they have apical and basal spines, the
achenes of Coontail lack spiny teeth along their sides. Another common
name of Ceratophyllum
is Common Hornwort.