LEMNACEAE 73 



4. SPATHYEMA Raf. 

 1. Spathyema foetida (L.) Raf. Skunk Cabbage. (Man. p. 231; 

 I. F./. S81.) In stramps, N. S. to Minn., Fla. and Iowa. — Pennsylvania : 

 Huntingdon; Lancaster; Northampton; Franklin; Chester; 

 DEi<A\vARE ; Allegheny. 



5. ORONTIUM L. 



1. Orontium aquatlcum L. Golden Club. (Man. p. 231 ; I. F./. 

 882.) In swamps and ponds, Mass. to Pa., Fla. and La., mostly near the 

 coast. — Pennsylvania ; Northampton ; Monroe ; Lancaster ; Cum- 

 berland ; Chester ; Huntingdon ; Delaware ; Lackawanna ; Som- 

 erset ; Pike. 



6. ACORUS L- 



1. Acoras Calamus L. Sweet Flag. Calamus-root. (Man. p. 

 231 ; I. F./. SSs- ) In wet places, N. S. to Minn., La. and Kans. Also in 

 Eu. and Asia. — Pennsylvania : Northampton ; Philadelphia, Point 

 Breeze ; Monroe ; Franklin ; Delaware ; Columbia ; Alegheny. 



Family 2. LEMNACEAE Dumort. Duckweed Family. 

 Plant-body much elongated or subglobose, not disk-like, rootless : propagative 



pouches solitary. i. Wolffia. 



Plant-body disk-like, with i or several roots : propagative pouches 2. 



Plant-body inconspicuously nerved : roots solitary on each plant, without a 



fibro-vascular bundle. ;:. Lemna. 



Plant-body conspicuously nerved : roots several, each with a fibro-vascular 

 bundle. 3. Spirodela. 



1. WOLFFIA Horkel. 



Plant-body smooth, somewhat flattened above, gibbous beneath, abundantly 

 brown-punctate. i. IV. punctata. 



Plant-body ellipsoidal or globose, with 2-3 papules on dorsal surface, not 

 punctate. 2. W. Columbiana. 



1. WolfSa punctata Griseb. Punctate Wolffia. (Man. p. 234.) 

 On the surface of stagnant waters, east of the Mississippi River from the 

 Lake region to the Gulf of Mexico — Pennsylvania : According to Britton, 

 Man. p. 234. 



2. Wolffia Columbiana Karst. Columbia Wolffia. (Man. p. 233; 

 I. F. /. 8go.) Floating on water, Ont. toN. J., Minn, and Mo., Mex. and 

 S. Am. — Pennsylvania: Philadelphia ; Bucks. 



2. LEMNA L. 



Plant-bodies long-stipitate, forming large submerged masses. 1. L. trisulca. 

 Plant-bodies sessile or short-stipitate, floating, more or less detached. 



Plant-body symmetrical or nearly so. 2. L. minor. 



Plant-body unsymmetrical. 3. L. perpusilla. 



1. Lemna trisulca L. Ivy-lEaved Duckweed. (Man. p. 232 ; I. F. 

 f. 88$. ) In still or flowing water, N. S. to Pacific coast, N. J. and N. 

 Mex., also in Eu., Asia, Africa and Australia. — Pennsylvania: Lan- 

 caster ; Northampton ; Mercer ; Chester. 



