442 LEMNACEiE. (duckwi:i:i) family.) 



with a 8in;;lc nmpliitrojious ovule. Stij^ma minute, sessile. Fruit green. Seed 

 without alliuiiuii. iMuhryo thick and ikshy. — A jjcrenniul utiuatic licrh, with 

 ol)lonj; lonii-petioled leaves, and a yellow erect spadi.K terminating tiie club- 

 shaped scape. 



1. O. aquaticum, L. Rhizoma deep, fleshy; leaves acute, nerved, on 

 stout terete pvtioles ; sca|)e terete, thickened upward, white beneath the spadix, 

 sheathed lirlow, commonly curved. — Ponds and slow-flowing streams, Florida, 

 and nortliward. March and Ainil. — Leaves about 1° long. Seapo l°-2° 

 long. Spadix 1'- 2' long; the u))pcr flowers mostly tetrandrous. 



7. ACORUS, L. Calamus. Sweet Flag. 



Scape flattened, leaf-like, with the lateral sessile spadix covered with the per- 

 fect flowers. Spathc none. Sepals and stamens 6. Corolla none. Filaments 

 slender: anthers kidney-shaped, 1 -celled, opening transversely. Ovary 2-3- 

 celled, witii several orthotropous suspended ovules in each cell. Stigma minute. 

 Fruit dry, gelatinous within, 1 - few-seeded. Embryo in the axis of the albu- 

 men. — Perennial herbs, from a creeping aromatic rhizoma. Leaves erect, long, 

 flattened, 2-cdged. Scape leaf-like, elongated above the spadix. 



L A. Calamus, L. — Wet places, Florida, and northward, apparently in- 

 troduced. April. — lliiizoma rather slender, pungent. Leaves l°-2° high, 

 linear-lanceolate. Scape narrower than the leaves. Spadix cylindrical, yellow- 

 ish, 2' -3' long, spreading. 



Order 136. LEMNACE^. (Duckweed Family.) 



Minute aquatic floating plants, with lenticular proliferous stems (fronds), 

 and usually simple roots, pendent from beneath. Flowers monoecious, 

 mostl}- from a marginal cleft of the stem. Spathe membranaceous, 

 pitcher-shaped, bursting into two unecjual lobes, soon vanishing, commonly 

 enclosing two sterile flowers, which are reduced to single slender filaments 

 bearing a 2-celled anther, and a single sessile 1-celled ovary, which forms 

 in fruit a 1 - 7-seeded utricU-. Embryo straight, in the axis of fleshy 

 albumen. 



1. LEMNA, L. Duckweed 



Spathcs marginal, 3-flowered. Anthers opening transversely Stigma funnel- 

 form. Ovules erect from the base of the cell, anatropous or half-anatropous. — 

 Stems increasing by lateral buds. Roots terminating in a calyptre-like append- 

 age. — The flowers of these plants are seldom seen. 



1. L. minor, L. Stems pale, round-obovate. flattened, single or variously 

 clustered ; root single ; ovule solitaiy, half-anatropous ; seed horizontal. — Pools, 

 ditches, &c., Florida, and northward ; common near the coast, and probably 

 intermixed with L. perpusilla, Torr — Stems l"-2" long. 



