246 



LEMNACEyE. 



Lemna. 



Ponds on Staten Island. Fl. and Fr. August. This species is much smaller than the 

 usual state of L. minor, and differs essentially in the ovary and fruit. It seems to connect 

 the genus Wolfia with Lemna. 



3. Lemna trisulca, Linn. Star Duckweed. 



Fronds oblong-lanceolate, stipitate, thin, denticulate at the tip; roots solitary. — Linn. sp. 2. 

 p. 970 ; Engl. bot. t. 920 ; Hook. fl. Land. t. 119 ; Muhl. cat. p. 86 ; Torr. fl. 1. p. 30 ; 

 Beck, bot. p. 383 ; Darlingt. fl. Cest. p. 9 ; Schleid. in Linn. I. c. p. 393 ; Kunlh, enum. 

 3. p. 5. 



Fronds half an inch to three-fourths of an inch long, membranaceous, translucent, atte- 

 nuated at the base into a stipe or tail, proliferous from the sides near the middle, at right 

 angles to the primary frond, and thus appearing cruciate. Flowers not seen. 



Ponds and stagnant waters. The flowers seem to be produced very seldom, and are very 

 little known even to European botanists. 



4. Lemna gibba, Linn. Gibbous Duckweed, 



Frond obovate, nearly fiat above, hemispherical underneath. — Linn. sp. 2. p. 970 ; Pursh, 

 fl. \. p.22; Torr.fl. 1. p. 31 ; L. C. Rich, in Guill. arch. 1. p. 200. t. 6 ; Drongn. I. c. 1. 

 p. 99. t. 12. /. 2 ; Wils. in Hook. bot. misc. 1. p. 145 ; Beck, bot. p. 383. Telmatophace 

 gibba, Schleid. in Linncea, 13. p. 391 ; Kunth, enum. 3. p. 6. 



" Fronds tumid and spongy underneath, each with a single root. Spathe very short. 

 Stamens 2; the filaments curved : anthers didymous; the cells subglobose. Ovary roundish, 

 one-celled : style about the length of the ovary : stigma concave, simple. Ovules several, 

 erect, anatropous. Fruit roundish, indehiscent, somewhat compressed. Seeds 1-5, ovoid; 

 testa coriaceous, costate." L. C. Richard. 



Stagnant waters near Liverpool, Onondaga county : found in flower {Pursh). Braddock's 

 Bay, Lake Ontario : not in flower. 



5. Lemna polyrrhiza, Linn. Greater Duckweed. 



Fronds roundish-obovate, palmately veined, flat above, slightly convex underneath ; roots 

 numerous, fasciculate. — Linn. sp. 2. p. 970 ; Pursh, fl. 1. p. 22; Engl. bot. t. 2458 ; Ell. 

 sk. 2. p. 519; Torr.fl. 1. p. 31 ; Beck, bot. p. 383; Darlingt. fl. Ccst. p. 9. Spirodela 

 polyrrhiza, Schleid. 1. c. p. 392 ; Kunth, enum. 3. p. 7. 



Fronds 3-4 lines long, succulent, throwing down a tuft of roots from near the centre ; 

 the under surface often dark purple. " Stamens 2. Ovary with 2 erect anatropous ovules." 

 Schleiden. 



Stagnant waters : much less common than L. minor. Never yet found in flower in North 

 America. 



