466 LEMNACE^E. (DUCKWEED FAMILY.) 



thick and fleshy. Perennial garlic-scented herbs, from a deep and thick 

 rhizoina, with large stout-petioled veiny leaves, and nearly sessile spathes, ap- 

 pearing before the leaves. 



1. S. foetidus, Salisb. Leaves thin, oval, cordate, short-petioled ; spathe 

 ovate, incurved, spotted with purple and yellow ; spadix dull purple, much 

 shorter than the spathe, enlarged in fruit. Bogs and swamps, North Caro- 

 lina, and northward. Feb. -March. Leaves I -2long. Spathe 2' -4' 

 long. Spadix in fruit 2' - 3' in diameter. Seeds about the size of a pea. 



5. ORONTIUM, L. GOLDEN-CLUB. 



Spathe none. Spadix cylindrical, covered with the yellow perfect flowers. 

 Sepals and stamens 4-6. Anthers 2-celled, opening lengthwise. Ovary 1- 

 celled, with a single amphitropous ovule. Stigma minute, sessile. Fruit 

 green. Seed without albumen. Embryo thick and fleshy. A perennial 

 aquatic herb, with oblong long-petioled leaves, and a yellow erect spadix ter- 

 minating the club-shaped scape. 



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

 stont terete petioles ; scape terete, thickened upward, white beneath the spadix, 

 sheathed below, commonly curved. Ponds and slow-flowing streams. 

 March -April. Leaves about 1 long. Scape l-2 long. Spadix l'-2' 

 long ; the upper flowers mostly tetrandrous. 



6. ACORUS, L. CALAMUS, SWEET FLAG. 



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

 perfect flowers. Spathe none. Sepals and stamens 6. Corolla none. Fila- 

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

 2-3-celled, with several orthotropons suspended ovules in each cell. Stigma 

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

 the albumen. Perennial herbs, from a creeping aromatic rhizoma. Leaves 

 erect, long, flattened, 2-edged. Scape leaf-like, elongated above the spadix. 



1. A. Calamus, L. Wet places, apparently introduced. April. 

 IJhizoma rather slender, pungent. Leaves l-2 high, linear-lanceolate. 

 Scape narrower than the leaves. Spadix cylindrical, yellowish, 2' -3' long, 

 spreading. 



ORDER 138. LEMNACEJE. (DUCKWEED FAMILY.) 



Minute aquatic floating plants, with lenticular proliferous stems 

 (fronds), and usually simple roots, pendent from beneath. Flowers 

 monoecious, mostly from a marginal cleft of the stem. Spathe mem- 

 lu-anaceous, pitcher-shaped, bursting into two unequal lobes, soon van- 

 ishing, 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 utricle. Embryo 

 straight, in the axis of fleshy albumen. 



