352 MAlirilLlACE.K rUuluriii. 



2. PILULARIA, Liiui. 

 Sporocarps globose, longitiuliually 2-4-ct;lItHl, dehiscent from the apex ; the cells 

 with parietal pluceuta-like cushions bearing in the upper portion niicrosporangia, 

 and below these numerous sporangia containing solitary niacrospores. — I'lants with 

 a slender creeping rhizome and tilitbrm leaves ; the sporocarps subsessile or i)eduncled 

 on the rhizome in the axils ol' the leaves. 



Five species are known. Tliey ^row in llie nuuMy borders of ponds and in occasionally inun- 

 dated jdaces in America, Europe, Northern Africa and Australia. 



1, P. Americana, Al. Braun. Leaves setiform, 1 inch long: sporocarps about 

 a line in diameter, attached by the side to a short descending j)eduncle, usually 

 3-celled; macrosi)ures in each cell 13 to 17, not constricted in the miildle. — ^lonatsb, 

 Acad. Berlin, 1863, 435, and 1872, G6G. Pilularia, ^'uttall, Fl. Arkans. 140. 



Near Santa Barbara {Mrs. Ellwood Cooper), May, 1879 ; Arkansas (Xutiall) ; also in Chili. 

 Less than half as large as the European P. tjluinli/eru, which has erect and regularly -J-cellcd 

 sporocarps. 



Order CXXV. SALVINIACE^. 



Floating plants with a more or less elongated and sometimes branching axis bear- 

 ing apparently distichous leaves : conceptacles very soft and thin-walled, two or 

 more on a common stalk, 1-celled and having a central often branched receptacle 

 which bears either macrosporangia containing solitary niacrospores, or microspit- 

 rangia containing numerous microspores. 



The order consists of two genera, S((Iviiii<i, not represented in the United States, and Azolht, 

 liaving each but very few species. The order is often united with the last, under the name of 

 llliizucarpcu;. 



1. AZOLLA, bam. 

 Small moss-like plants, the stems pinnately branched, coveretl with minute imbri- 

 cating 2-lobed leaves, and emitting rcxjtlets on the underside. Concei)tacles in pairs 

 beneath the stem, either both containing macrospores, or one of each kind : smaller 

 conceptacles acorn-shaped, containing at the base a single macrosi)ore, and in the 

 upper part several corpuscles of unknown character. Larger ci>nceptacles globose, 

 having a basal ])lacenta which produces man}' pedicelled sj)orangia containing sev- 

 eral masses of microspores. 



In a paper on Azolhi Nilotka by Metteniiis (in Plautiu Tinneau;e) is found one of the best 

 attempts to explain tlie curious fructilication of this genus. Four species are described. 



1. A. Caroliniana, Willd. Plant 4 to 12 lines broad, much branched : leaves 

 witli ovate lubes, inferior lube reddish, superior one green with a reddish bcrder : 

 corpuscles three to each macrosporangium ; macrospori;s with a miinitely granulate 

 surface: masses of microspores glochidiate. — Sp. 1*1. v. 541 ; Mettenius, Liiuuea, 

 XX. 278, t. 3, fig. 9-15, and PI. Tinneame, 53; Cray, Manual, 5 ed. GOG, t. 14. 

 A. microphylla, Kaulf. Enum. 273. 



Floating, conmionly on quiet waters, not rare. Oregon to Arizona, eastwaid to the AtlaiUic, 

 and southward to Brazil. An inconspicuous jilant, looking like a purplish Hepatic moss. 

 A. Maijdlanka is kept ajiart by Mettenius under the name iA' A. Jiliculoidis, Earn. 



