66 LEMNACEAE. 



diameter, the berries green. Common, in swamps and low meadows. Spr. 

 SKUNK- CABBAGE. 



4. OE.ONTIUM L. Swamp herbs. Leaves with relatively narrow blades. 

 Spadix terminal, elongate, subtended by the thin spathe, the scape pliable, soon 

 weak. Flowers perfect. Perianth of 4-6 scale-like members (6 below, 4 above). 

 Fruits not immersed. 



1. O. aquaticum L. Eootstock deeply buried. Leaf -blades oblong or elliptic, 

 1-3 dm. long: spadix golden-yellow, 2-6 cm. long. Eather rare, in swamps, 

 ponds or streams. Spr. GOLDEN-CLUB. BOG-TORCHES. FIRE-LEAF. 



5. ACORTJS L. Swamp or meadow herbs with aromatic rootstocks. Leaves 

 with linear blades. Spadix lateral, elongate, at the base of the linear spathe. 

 Flowers perfect. Perianth of 6 concave members. Fruits crowded. 



1. A. Calamus L. Eootstock horizontal: leaves 5-20' dm. tall: scape resembling 

 the leaves: spathe erect: spadix yellowish, 3-8 cm. long. Common, in low 

 grounds and swamps. Spr. and sum. CALAMUS. SWEET-FLAG. 



FAMILY 2. LEMNACEAE. DUCKWEED FAMILY. 



Floating herbs, consisting chiefly of very small, often minute, fleshy 

 structures, sometimes with 1 or several roots. Propagative pouches 1 or 

 2 in each body. Flowers monoecious, one or two staminate and one 

 pistillate in a propagative pouch. Staminate flowers consist of 1 stamen. 

 Pistillate flowers consist of 1 carpel. Fruit a utricle. 



Root solitary, without a fibro-vascular bundle : plant-body inconspicuously nerved. 



1. LEMNA. 



Roots several, each with a fibro-vascular bundle : plant-body con- 

 spicuously nerved. 2. SPIRODELA. 



1. LEMNA L. Plant-body disk-like, inconspicuously nerved. Anther-sacs 

 opening transversely. Utricle somewhat flattened, often ribbed. Sum. 

 DUCKWEED. 



Plants growing in large submerged masses ; bodies long-stipitate. 1. L. trisulca. 



Plants floating, more or less detached ; bodies sessile. 2. L. minor. 



1. L. trisulca L. Eoot-sheath acute: plant-bodies both submerged and aerial, 

 often falcate, 5 10 mm. long, acute: aerial plants smaller than the submerged 

 and short-stalked, cavernous ; submerged plants with twisted stipes. M. Eare, 

 in ponds. Limestones. 



2. L. minor L. Eoot-sheath obtuse: plant -bodies elliptic, obovate, or sub- 

 orbicular, 2-4 mm. long, mostly 3-nerved, commonly keeled on the back and 

 papillose on the midrib: seeds 12-15-ribbed. Susquehanna valley. Eather 

 rare, in ponds. 



2. SPIBODELA Schleid. Plant-body disk-like, conspicuously several- 

 nerved. Anther-sacs opening lengthwise. Utricle lenticular, with winged 

 margins. 



1. S. polyrhiza (L.) Schleid. Plants mostly sterile and perennial. Eoots 4-16: 

 plant -body obovate or suborbicular, 2.5-8 mm. long, 5-15-nerved: seeds smooth. 

 N. M. Eather common, in ponds and along streams. Sandstones and 

 shales, limestones. Sum. 



