20. E. pygmæ̀a, Torr. Culms bristle like, flattened and grooved (1–2´ high); spikelet ovate, 3–8-flowered; scales ovate (greenish), the upper rather acute; achene ovoid, acutely triangular, smooth and shining, tipped with a minute tubercle; bristles mostly longer than the fruit, sometimes wanting.—Brackish marshes, from N. Brunswick to Fla.
[*][*] Tubercle continuous with the nutlet and not contracted at base.
21. E. pauciflòra, Link. Culms striate-angled, very slender (3–9´ high), scarcely tufted, on slender running rootstocks, with a short truncate sheath at base; scales of the ovate spikelet evidently 2-ranked, chestnut-brown, pointless, all flower-bearing, the two lower larger; bristles 3–6, about as long as the conspicuously beaked triangular achene. (Scirpus pauciflorus, Lightfoot.)—Wet places, N. Y. to N. Ill. and Minn., north and westward. (Eu., Asia.)
5. DICHRÒMENA, Richard. ([Pl. 4.])
Spikelets aggregated in a terminal leafy-involucrate head, more or less compressed, few-flowered, all but 3 or 4 of the flowers usually imperfect or abortive. Scales imbricated somewhat in 2 ranks, more or less conduplicate or boat-shaped, keeled, white or whitish. Stamens 3. Style 2-cleft. Perianth, bristles, etc., none. Achene lenticular, wrinkled transversely, crowned with the persistent and broad tubercled base of the style.—Culms leafy, from creeping perennial rootstocks; the leaves of the involucre mostly white at the base (whence the name, from δίς, double, and χρῶμα, color).
1. D. leucocéphala, Michx. Culm triangular (1–2° high); leaves narrow; those of the involucre 4–7; achene truncate, not margined.—Damp pine-barrens, N. J. to Fla. Aug., Sept.
2. D. latifòlia, Baldwin. (Pl. 4, fig. 1–5.) Culm stouter, nearly terete; leaves broadly linear, those of the involucre 8 or 9, tapering from base to apex; achene round-obovate, faintly wrinkled, the tubercle decurrent on its edges.—Low pine-barrens, Va. to Fla.
6. PSILOCÁRYA, Torr. Bald-rush. ([Pl. 4.])
Spikelets ovoid, terete, the numerous scales all alike and regularly imbricated, each with a perfect flower. Perianth (bristles) wholly wanting. Stamens mostly 2. Style 2-cleft, its base or the greater part of it enlarging and hardening to form the beak of the lenticular or tumid more or less wrinkled achene.—Annuals, with leafy culms, the spikelets in terminal and axillary cymes. (Name from ψιλός, naked, and καρύα, nut.)
1. P. scirpoìdes, Torr. Annual (4–10´ high), leafy; leaves flat; spikelets 20–30-flowered; scales oblong-ovate, acute, chestnut-colored; achene somewhat margined, beaked with a sword-shaped almost wholly persistent style. (Rhynchospora scirpoides, Gray.)—Inundated places, S. N. Eng.