Herbs aquatic, small, with opposite, simple, entire leaves. Flowers axillary, solitary, very minute, polygamous, achlamydeous, with 2 colored bracts. Stamen 1, rarely 2; filament slender; anthers 1-celled, 2-valved, reniform. Ovary 4-celled, 4-lobed; ovules solitary. Styles 2; stigmas simple points. Fruit 1-celled, 4-seeded, indehiscent Seeds peltate, albuminous.
Genua 1, species 6, growing in stagnant waters, both of Europe and America.
CALLIT'RICHE, L. (Gr. beautiful, hair; alluding to the slender stems.) Character the same as that of the order. -
1 C. verna L. Floating; lvs. obovate-spatulate, 3-nerved, the lower more narrow or linear; fls. subsessile; bracts 2, longer than the ovary; fr. obtusely margined, obcordate. - A little aquatic, common in pools and ditches. Sts. numerous, slender, consisting of 2 tubes, 8 to 12 to 20' long, according to the depth of the water. Lvs. 4 to 6" long, with the tapering base, 1/2 to 2" wide, the floating broadest. The fls. solitary, rarely 2 in the axil, the outer a stamen only. Bracts white. Stamen posterior, yellow, styles 2, filiform, anterior. Caps. 1/2" long, suboval. Apr. - Jl (C. intermedia Willd. C. heterophylla Ph. C. aquatica Bw.)
2 C. autumnalis L. Floating; lvs. all linear, 1-nerved, or the highest linear-spatulate; fls. subsessile; bracts shorter than the ovary or none; fr. oval, acutely margined. - In similar situations with the first, S. States, less common. Sts. 1 to 2f long. Lvs. 5 to 7" long, often bifid, a few of the highest 3-veined. May - Sept (C. linearis Ph.)
3 C. terrestris Raf. Sts, short, diffuse, prostrate; lvs. very small, oblong, all similar, fls. sessile, 2-bracted; fruit broader than long, deeply obcordate, 2-winged on the margins. - A much smaller species, on the muddy borders of ponds, covering the surface. Sts. 1 to 2' long. Lvs. 1 to 2" long. Fr, 1/4" long, Jn. - Aug. (C. brevifolia Ph. C. platycarpa Kutz.)