1. H. vulgàris, L. Stems simple (1–2° high); leaves in whorls of 8 or 12, linear, acute; fruit nearly 1´´ long.—Ponds and springs, Penn. to Ind. and Minn., and northward. (Eu.)
4. CALLÍTRICHE, L. Water-Starwort.
Flowers monœcious, solitary or 2 or 3 together in the axil of the same leaf, wholly naked or between a pair of membranaceous bracts. Sterile flower a single stamen; filament bearing a heart-shaped 4-celled anther, which by confluence becomes 1-celled, and opens by a single slit. Fertile flower a single 4-celled ovary, either sessile or pedicelled, bearing 2 distinct and filiform sessile, usually persistent stigmas. Fruit nut-like, compressed, 4-lobed, 4-celled, separating at maturity into as many closed 1-seeded portions. Seed pendulous, filling the cell; embryo slender, straight or slightly curved, nearly the length of the oily albumen.—Low, slender and usually tufted, glabrous, or beset with minute (microscopic) stellate scales, with spatulate or linear entire leaves, both forms of leaves often occurring on the same stem. (Name from καλός, beautiful, and θρίξ, hair, from the often almost capillary stems.)
[*] Small annuals, forming tufts on moist soil, destitute of stellate scales; leaves uniform, very small, obovate or oblanceolate, 3-nerved, crowded; bracts none.
1. C. defléxa, Braun. var. Austìni, Hegelm. Stems ½–1´ high; fruit small ({1/3}´´ broad), broader than high, deeply notched above and below, on a pedicel often nearly of its own length or nearly sessile; lobes of the fruit narrowly winged and with a deep groove between them; persistent stigmas shorter than the fruit, spreading or reflexed; leaves 1–2´´ long. (C. Austini, Engelm)—On damp soil, N. Y. and N. J. to Ill., Mo., and Tex. (S. Am.)
[*][*] Amphibious perennials; leaves with stellate scales, the floating ones obovate and 3-nerved, the submersed linear (all uniform and narrow in terrestrial forms) flowers usually between a pair of bracts.
2. C. vérna, L. Fruit (½´´ long) higher than broad, obovate, slightly obcordate, usually thickest at the base, sessile, its lobes sharply keeled or very narrowly winged above, and with a wide groove between them; stigmas shorter than the fruit, almost erect, usually deciduous; floating leaves crowded in a tuft, obovate, narrowed into a petiole.—Common in stagnant waters, Penn. and N. J. to Fla., west to Minn., Tex., and the Pacific. (Eu.)
3. C. heterophýlla, Pursh. Fruit smaller, as broad or broader than high, deeply emarginate, thick, almost ventricose, sessile or nearly so, its lobes obtusely angled, with a small groove between them; stigmas as long as the fruit, erect, persistent; floating leaves crowded in a tuft, broadly spatulate, often retuse, abruptly narrowed into a long petiole.—Stagnant water, N. Y. and N. J. to S. Ind. and Mo.
[*][*][*] Submersed perennial, with numerous uniform linear 1-nerved leaves; flowers without bracts; carpels separate nearly to the axis.
4 C. autumnàlis, L. Stems 3–6´ high; fruit large (1´´ wide or more), flattened, circular, deeply and narrowly notched, sessile or nearly so, its lobes broadly winged, and with a very deep and narrow groove between them; stigmas very long, reflexed, deciduous; leaves all linear from a broader base, retuse or notched at the tip (2–6´´ long).—W. Mass., Lake Champlain and N. New York, Lake Superior, and westward. (Eu.)