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ENDOGENOUS PLANTS. 



ORDER C. LEMNA V CEAE. 



Minute stemless herbaceous aquatics, floating free on stagnant pools ; leaves, as well 

 as stem, substituted by a flat/rond, which produces 1 or 2 monoicous florets from a 

 chink at the edge, or upper surface, and a few pendulous radicles from the under 

 surface; stamen 1 ; fruit utricular; embryo straight, in the axis of fleshy albumen. 

 Of this remarkable Order, Prof. A. GRAY observes: "Fructification much as in the 

 Arum Family, of which these plants are minute and greatly reduced forms." 



4O6. LEM'tfA, L. 



[An ancient Greek name; of uncertain meaning.] 



Flowers 3 together, in a cleft in the edge of the frond, bursting 

 through a thin membranaceous urceolate spathe; two of them con- 

 sisting of single stamens (one preceding the other), with thread-like 

 filaments, and 2-celled anthers; the third floret a 1-celled ovary ; 

 ovule mostly solitary, erect; style elongated, recurved; stigma fun- 

 nel-form. Utricle 1 -seeded, indehiscent. Annuals. Fronds laterally 

 proliferous by a kind of buds formed in the chinks, as well as prop- 

 agated by seeds ; roots with a sheath-like appendage on the end ; 

 flowers microscopic, rarely found (never yet, in this country. Prof. 

 A. GEAY). 



t Fronds learing single roots; ovule solitary. 



! tj minor, L. Fronds roundish-obovate, or oval, sessile, thick- 

 ish, proliferous from near the base. 

 LESSER LEMNA. Duck's-meat. Duck-weed. 



Fronds about a line, or line and half, in length, slightly convex beneath, some- 

 what succulent, green. Soot a solitary fibre, from the centre of the frond, rather 

 elongated. 

 Hob. Pools, and stagnant waters: frequent. Fl. Fr. 



Obs. These singular little plants, as ENDLICHER remarks, are 

 "nemini non cognitae" known to every body, especially this 

 species; but they are so minute, that their organs are seldom seen, 

 and are imperfectly understood. 



%. I*, trisulca, L. Fronds elliptic-oblanceolate, petiolate, thin, 

 denticulate at apex, proliferous from the sides. 

 THREE-FURROWED LEMNA. 



Fronds % to % of an inch long, nearly pellucid, finally elongated and narrowed 

 at base to a slender tail, or petiole, obtuse at apex, proliferous from near the mid- 

 dle of the sides, so as to form crosses. While these lateral fronds remain sessile, 

 they present the appearance of a 3-lobed leaf. 

 Hob. Stagnant waters ; New Garden : not common. Fl. Fr. 



ff Fronds learing a fascicle of roots; ovules 2. 



3. IL. polyrliiza, L. Fronds roundish-obovate, thickish, pal- 

 mately veined, proliferous from near the base. 

 MANY-ROOTED LEMNA. 



Fronds 2 to 4 lines in length, of a rather firm texture, and often dark purple 

 beneath, with a little cluster of radicles from near the centre. 

 Hob. Stagnant pools; along Schuylkill : not common. Fl. Fr. 



