430 LEMNAOEJE. (DUCKWEED FAMILY.) 





tile larger, consisting of numerous sessile pistils, each surrounded by 3 - scales 

 much like a calyx. Fruit nut-like when mature. Roots fibrous. Stems sim- 

 ple or branching, sheathed below by the base of the linear leaves. (Name from 

 crrapyavov, a Jillet, from the ribbon-like leaves.) 



# Inflorescence mostly branched, icith numerous heads, the 1-3 lower fertile, the rest 

 sterile: stiywas often 2, linear, much longer than the style: stems stout, erect (2 

 3 high) : leaves erect ('-$' wide), flat and merely keeled, the base triangular with 

 concave sides : fruit sessile. 



1. S. euryciirpilill, n. sp. Engclm. Fruit many-angled (3" -4" long), 

 with a, broad and depressed or retu.se summit (2$" wide), abruptly and slightly tipped 

 in the centre; head globose, 1' wide when ripe. Borders of ponds, &c., com- 

 mon northward and especially westward. June - Sept. 



2. S. r:iiH4>Siiiil, Hudson. Fruit somewhat triangular, with the summit 

 hemispherical and pointed, smaller than in the last. Same situations, northward 

 and eastward. July -Sept. (Eu.) 



* # Inflorescence mostly simple : stigma single : stem slender. 



3. S. Simplex, Hudson. Fertile and sterile heads each 3 or 4, the lattei 

 or some of them mostly pedunclcd ('-' broad) ; fruit abruptly contracted at the 

 summit ii to a slender beak as long as itself; stigma linear; leaves triangular at 

 the base with flat sides (6'- 18' long). (S. Americanum, Nutt.) Along streams 

 and pools; common northward and eastward. (Eu.) 



4. S. nfitans, L., var. n III lie, Fries. Heads few, the fertile 1 - 3 ; stig 

 ma short ; fruit oblong, slender-beaked as in No. 3, also attenuate into a stalk-like 

 base; leaves very long and flaccid, floating. (S. affine, Schnitzlein.) In ponds and 

 slow streams, New England, New York, and northward. This may be the S. 

 angustifolium of Michaux, as is generally thought; but Fries assigns that to 

 the next. (Eu.) 



5. S. clllgUStifolillin, Michx. Small and slender ; fruit more triangu- 

 lar, scarcely beaked, short-pointed, not contracted at the base ; leaves long and nar- 

 row (l"-2" wide) and floating when growing in water, scarcely surpassing tho 

 stems in dwarf states, growing nearly out of water (5'-8' high). New England 

 to Wisconsin and northward. Fruiting heads only 2"-3 ' in diameter. (Eu.) 



OiiDER 114. LEMNACEJE. (DUCKWEED FAMILY.) 



ATmute utemJ^ss plants, fextting free on the water, destitute of distinct stem 

 and foliage, being merely a flat frond, producing few monoecious flowers froln 



a chink (it the edye or upper surface, and usually hanging roots from under- 

 neath : ovules erect from the base of the cell. Fruit a I- 1 -seeded utricle 

 Emlruo strn'ujhl, in the axis of fleshy albumen. A little group of plants, 

 of peculiar mode of growth, in character mostly intermediate between the 

 Arum Family and (lie following, to one or the other of which it may be 

 joined. The, Linmean genus Lemna has been divided into three genera, 

 I answering to the following sections,) possibly with sufficient reasons ; but 

 it is not worth while to adopt them here, since the flowers and fruit arc 

 rarely met with. 



