524 FLORA OF TEXAS. 



11 ate and supported by a cup-shaped involucre, the fertile 

 solitary ; calyx and corolla none ; anther-coWs 3-8, opening 

 transversely; ovary 1-celled, with several erect orthotro- 

 poiis ovules ; style thick ; stigma disk-like ; berry few-many- 

 seeded ; embryo at the apex of the albumen. — Small free- 

 floating aquatic herbs, with fibrous roots, and entire 

 clustered spreading leaves, with the flowers in their axils. 



P. SPATHULATA, Miclix. Leaves arranged in a circle, 

 round-obovate, abruptly contracted into a short petiole, 

 with the nerves projecting beneath (lamelliform) ; roots 

 numerous, elongated ; spatlie short-peduncled, white. In 

 still water. Leaves l'-2' long. 



ACORUS, L. Calamus ; Sweet Flag. 



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

 covered with the perfect /?o?6'er5 ; spathe none; sepals and 

 stamens 6 ; corolla none ; filame^its slender ; anthers kid- 

 ney-shaped, 1-celled, opening transversely; ovary 2-3- 

 celled, with several ortliotropous 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. 



A. CALAMUS, L. Wet places. April. Rhizoma rather 

 slender, pungent; leaves l°-2° high, linear-lanceolate; 

 scape narrower than the leaves ; sp>adix cylindrical, yellow- 

 ish, 2-3' long, spreading. 



128. DUCKWEED FAMILY. Order, Lemxace^. 



Minute aquatic floating 7;/«?2 ^5, with lenticular prolifer- 

 ous stems (fronds), and usually simple roots pendent from 

 beneath; /7o?r^?'.^ monoecious, mostly from a marginal cleft of 

 the stem ; spathe membranaceous, pitcher-shaped, bursting 

 into two unequal lobes, soon vanishing, commonly.inclosing 



