Curly pondweed is a perennial and has elongate, slender rhizomes that
are buff or reddish. The stems of curly pondweed are flattened. Leaves
are entirely submersed, sessile, oblong to broadly linear, 3 to 8 cm long
and 5 to 12 mm wide. The leaf tip is usually rounded and sometimes minutely
cuspidate. The leaf margins are finely toothed, undulate and crisped.
Stipules are translucent and soon disintegrating. Bur-like turions that
are up to about 5 cm long often form during the spring and late summer
months and consist of three to seven small, thickened leaves that project
from the stem at a slight upward angle. Flowers are borne on a short spike
that extends above the surface of the water. The fruits are flat, 4 to
6 mm long (including the beak) and have a distinct, pointed beak that
is erect or somewhat curved and about 2 to 3 mm long.
Potamogeton crispus grows in lakes, reservoirs, ponds, rivers, streams,
and springs. It can grow in clear to turbid and polluted waters and in
alkaline or brackish waters (Stuckey 1979). Curly pondweed produces seed,
but the importance of seed in the spread and maintenance of populations
is unknown (Stuckey 1979) and is assumed to be less important than turions
(Sastroutomo 1981). In most portions of its range, Potamogeton crispus
typically reaches peak biomass in the late spring or early summer months,
forms turions, then declines and "survives" the warmer months
in a dormant state (i.e., as a turion) (Cypert 1967, Stuckey 1979, Sastroutomo
1981, Tobiessen and Snow 1984, Nichols and Shaw 1986). As water temperatures
cool during the late summer or fall months, the turions germinate, grow
through the winter months with the plants reaching peak biomass in the
spring before most other submersed macrophytes begin their growth cycle.
Once established, the plants regrow and form colonies from rhizomes.
Dense colonies of curly pondweed can restrict access to docks and sport
fishing areas during spring and early summer months. Because populations
of curly pondweed usually decline during the summer months, it does not
directly compete with many of the native submersed species.