AZOLLA. 



SALVINIACEiE. 



513 



2. AZOLLA. Lam. enc. 1. p. 343; R. Br. prodr. p. 166. AZOLLA. 



[Said to be from the Greek, azo, to dry, and oUumi, olio, to destroy ; being easily killed by dryness.] 



Involucres ovoid, membranaceous, sessile on the underside of the branches ; the sterile ones 

 opening transversely all around, containing an oval somewhat fleshy body arising from the 

 base, and bearing a short column which supports three anther-like lobes at the summit, 

 which cohere with a kind of calyptra : fertile? involucres much larger, opening irregularly, 

 filled with numerous pedicellate globular capsules, each containing about 5 roundish hairy 

 grains or spores. — Minute floating plants, pinnately or radiately branched. Stems filiform. 

 Leaves imbricated, alternate. 



1. Azolla Caroliniana, Willd. Carolina Azolla. 



Leaves ovate-oblong, obtuse, spreading, reddish underneath. — Willd. sp. 5. p. 541 ; 

 Pursh, fl. 2. p. 672 ; Torr. compend. p. 390 ; Beck, hot. p. 463. 



Whole plant only half an inch or an inch in length, resembling a Jungermannia, dark 

 green tinged with purple, branching repeatedly in a pinnated or radiating manner. Leaves 

 scarcely more than one-third of a line in length. Sterile involucres solitary or in pairs, at 

 the base of the fertile ones ; the upper part discolored, separating transversely, filled with a 

 body which is by some supposed to perform the office of a stamen ; the anther-like lobes 

 bent down and applied to the short column. Fertile involucres 4-5 times larger than the 

 sterile, containing 25 - 30 spherical capsules, the pedicels of which radiate from the base of 

 the involucre. Spores or grains roundish, sparingly furnished with radiating hairs. 



In slowly flowing waters, island of New-York ; floating on the waters of Lake Ontario 

 (Pursh); Braddock's Bay (Dr. Bradley). Sir William Hooker refers A. microphylla of 

 Kaulfuss to this species, which he suspects is not distinct from the original A. Magellanica. 

 In the United States it is widely diffused, but very rare north of Georgia. 



[Flora — Vol. 2.] 



65 



