Aquatic and Wetland Vascular Plants of the Northern Great Plains
43. Callitrichaceae, the Water Starwort Family
1. Callitriche L. -- Water starwort
2. Callitriche heterophylla Pursh
Submersed aquatic or seldom stranded on mud, with stems 0.5-2 dm long. Leaves
usually of 2 basic types, with linear, submersed leaves below on the stems and
obovate to spatulate floating leaves upward, the leaves seldom all of one type;
submersed leaves 10-20 mm long, 0.5-1.2 mm wide, 1-nerved, bidentate
at the tip, the pairs connected at their bases by a ridge or narrow wing; floating
leaves in terminal rosettes or partly scattered along the stem, 6-15 mm long,
3-7 mm wide, 3- to 5-nerved, rounded at the tip, attenuate to the base, connected
at their bases like the linear leaves, the transition from submersed to floating
leaf types gradual. Flowers subtended by a pair of hyaline bracts, these
deciduous. Fruits 0.6-1.2 mm long, about as wide, slightly broader toward
the tip than the base, the segments convex on the face and rounded on the back,
not wing-margined, irregularly pitted on the surface. Jun--Sep. Shallow water
or mud of springs and stream pools; rare, with collections from Lawrence and
Harding Cos., SD, also w MN; (N.S. to s MN and w SD, s to FL and TX; also w
MT to WA, s to CA and C.Amer.).