OPHIOGLOSSACE^E. (ADDEK's-TONGTJE FAMILY.) 437 



1. Marsilia. Conceptacles somewhat crustaeeous, several-celled, containing both macro- 



spores and microspores, solitary and peduncled. Leaves peltately quadrifoliolate, 

 with elongated petioles. 



2. Azolla. Conceptacles very soft and thin-walled, one-celled, containing either macro- 



sporangia with solitary macrospores or microsporangia with numerous microspores, 

 in pairs beneath the pinnately branched stems. Leaves minute, imbricated, and 

 2-lobed, apparently distichous. 



1. MARSILIA, L. 



Conceptacles ovoid or bean-shaped, composed of 2 vertical valves and' 

 several transverse compartments in each valve ; their peduncles rising either 

 from the petiole or the rhizome. — Plants with slender creeping rootstocks, 

 growing in the mud under shallow water, with the leaves floating, or some- 

 times terrestrial. 



1. M. vestita, Hook. & Grev. Leaflets broadly cuneate, usually hairy, 

 entire, 2 to 7 lines long and broad ; petioles 1 to 4 inches long : peduncles 

 free from the petiole : sporocarps short-peduncled, about 2 lines long, very 

 hairy when young. — From Texas to Oregon and California. In Yellowstone 

 Park ( Coulter). 



2c AZOLLA, Lam. 



Small moss-like floating plants, the pinnately branched stems covered with 

 minute imbricated leaves and emitting rootlets on the under side: the 

 paired conceptacles either both containing macrospores, or one of each kind ; 

 smaller conceptacles acorn-shaped, containing a single macrospore ; larger 

 conceptacles globose, and having a basal placenta which produces many pedi- 

 celled sporangia containing masses of microspores. 



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

 leaves with ovate lobes, inferior lobe reddish, superior one green with a red- 

 dish border : macrospores with a minutely granulate surface : masses of 

 microspores glochidiate. — Floating on quiet waters, from Oregon to Arizona 

 and eastward to the Atlantic. 



Order 95. OPHIOGLOSSACE^. (Adder's-Tongue 

 Family.) 



Leafy plants; the leaves (fronds) simple or branched, erect in 

 vernation : spores of one kind, borne in special spikes or panicles 

 in sporangia (without an elastic ring), which are formed by groups 

 of cells in the interior of the fruiting segments of the frond : prothallus 

 underground, destitute of chlorophyll. 



1. BOTRYCHIUM, Swartz. Grape-Fern. Moonwort. 



Fronds with a posterior pinnatifid or compound sterile segment and an 

 anterior panicled fertile segment, the separate sporangia in a double row on 

 the branches of the panicle : bud enclosed in the base of the stalk. 



