562 



ORDER CXLI. CYPERACK^E. 



Genus X.— DICHRO'MENA. Vahl. 3—2. 

 (From d is, two, and chroma, color, alluding to the whit© and green of the flowers.) 



Glumes imbricate on all sides; the lower ones without flow- 

 ers. Palece none. Seed naked. 



1. D. LEUCOCErn'ALA, (Mich.) Stem erect, triangular, naked. Leaves 

 linear, glabrous, concave. Flowers in compound heads ; involucre 6- 

 leaved, white at the base, the three exterior ones longest. Glumes 

 membranaceous, lanceolate, white. — 2f. July — Oct. Damp soils. 10 

 — 12 inches. 



2. D. latifo'lia, (Ell.) Stem erect, glabrous, leafy at the base, te- 

 rete. Leaves usually longer than the stem, concave, with long sheaths. 

 Flowers in compressed heads, compound ; involucre about 10-leaved, the 

 exterior ones longest, tapering toward the summit, white. Glumes 

 ovate, white. — 2f. May — June. On the margins of ponds. 10 — 18 in. 



Genus XL— RHYNCOS'PORA. Vahl. 

 (From rhyncos, a beak, and spora, a seed.) 



Glumes collected into a spike ; inferior ones without flowers. 

 Po.lece none. Seed 1, crowned with a persistent style, surround- 

 ed by bristles. 



1. R. longiros'tris, (Ell.) Stem triangular, erect, glabrous. Leaves 

 linear-lanceolate, channeled, glabrous. Flowers in corymbose panicles, 

 axillary and terminal. Glumes usually 6, with the flowers between the 

 fifth and sixth glumes. Seed compressed, terminated by a long per- 

 sistent style. — 2f • July — Oct. Wet places. 3 — 6 feet. 



2. R. al'ba, (Lind.) Stem slender, glabrous, 3-angled at the summit. 

 Leaves linear, channeled, glabrous. Spikes in corymbose clusters, ax- 

 illary and terminal. Glumes nearly white. Seed tuberculate, surround- 

 ed by 10 bristles. — 0. May — June. Common. 10 — 12 inches. 



3. R. cilia'ta, (Vahl.) (R. punctata, Ell.) Stem triangular, slender. 

 Leaves linear-lanceolate, with scabrous margins. Flowers in lateral and 

 terminal fascicles, clustered at the summit. Glumes mucronate. Seed 

 compressed. — If. July — Aug. Damp places. 1 — 2 feet. 



4. R. gi.omera'ta, (Vahl.) (R. capitellata, Ell.) Stem erect, trian- 

 gular. Flovxrs in spherical, axillary heads. Leaves setaceous, shorter 

 than the stem. Seed compressed, surrounded by scabrous bristles. — 

 2f . May— Sept. Wet places. 1 — 2 feet. 



5. R. msTANs, (Vahl.) (R. cymosa, Ell.) Stem terete, erect. Leaves 

 linear, glabrous, concave. Flowers in axillary and terminal panicles. 

 Qlitmei usually 6, with the outer ones ferruginous, the inner one white, 

 2-flowered. Seed compressed, oval. Bristles 6. — If. Through the 

 summer. Bogs and ditches. 1 — 3 feet. 



6. R. plumo'sa, (L.) Stem erect, glabrous, 3-angled, slender. Leaves 

 linear, with scabrous margins. Flowers terminal, crowded. Glumes 

 ovate, awned. Seed rugose, with 6 plumose bristles. — 2f. June — 

 Aug. Pine-barrens. 8 — 12 inches. 



7. R. inkxi'an'sa, (Vahl.) Stem somewhat triangular, generally in- 

 clined. Leaves linear, channeled. Flower* in axillary and terminal 



