SA L VINIA CE^E. 1 2 7 



ing peduncle, usually 3-celled ; macrospores 13 17 in each cell, 

 not constricted in the middle. Santa Barbara, California 

 (Mrs. Cooper), Arkansas {Nuttall). 



ORDER III. SALVINIACE^E. 



Floating plants with a more or less elongate and sometimes 

 branching axis bearing apparently distichous leaves. Sporo- 

 carps soft, thin-walled, two or more on a common stalk, i-celled, 

 with a central, often branched receptacle which bears macro- 

 sporangia containing a single macrospore, or microsporangia 

 containing numerous microspores. Consists of the two follow- 

 ing genera. 



I. Salvinia Sclireb. Leaves 6" 9" long, with a distinct 

 midrib. 



II. Azolla Lam. Leaves minute, numerous, closely imbri- 

 cate, deeply lobed. 



I. SALVINIA Schreb. 



Floating annuals with slender stems bearing small two- 

 ranked leaves. Sporocarps arranged in clusters, globose, mem- 

 branous, i 2 of each cluster containing 10 or more macro- 

 sporangia, the others containing numerous smaller microspo- 

 rangia. Named for Salvini, a Florentine professor. Contains 

 thirteen species, one of which is found with us. 



i. S. natans Hoffm. Leaves oblong, horizontal, rounded 

 or slightly cordate at base, ' i' long, bright green above, the 

 under surface matted with brown, pellucid hairs ; sporocarps 

 4 8 in a cluster. (Marsilia natans L.) Bois Brule Bottoms, 

 Perry County, Missouri (Demetrio.) Reported by Pursh from 

 Central New York; the exact station unknown. 



I. AZOLLA Lam. 



Small, moss-like plants with pinnately branched stems cov- 

 ered with minute, imbricate, 2-lobed leaves, and emitting rootlets 

 beneath. Sporocarps of two kinds, borne in the axils of the 

 leaves. Smaller sporocarps ovoid, containing a single macro- 

 spore at the base. Larger sporocarps globose, producing from 

 the base many pedicelled sporangia, containing several masses 



