672 HTDKOPTERIDBS. 



forking, and terminated by the sliort (4"- 6") nodding spike; leaves about 

 6-rowed, linear-subulate, entire, spreading or recurved ; those of the spike 

 ovate, acuminate, with bristly margins. — Springy sandy places. East Florida 

 {Curtiss), and Alabama {Mohr). 



Oedbr HYDROPTERIDES. 



MABSILIA, L. 



Plants with filiform creeping stems, a whorl of 4 wedge-shaped leaves at 

 the summit of a long erect petiole, and one or more globular sporangia 

 borne on a slender stalk at the base of the petioles, each divided into sev- 

 eral partitions, which contain the larger and smaller spores. 



S. uucinata, A. Braun. Stem long; leaves smooth or hairy; sporangia 

 oval, compressed, half as long as the peduncle. — Banks of the JMississippi 

 below Vicksburg. 



ISOETES, L. 



I. melanospora, Engelm. Small, mostly monoecious; leaves few (5- 

 10), distichous (2' -2^' long) ; spore-cases covered by the thin edges of the 

 cavity (velum); larger spores blackish, very minutely warty, the smaller 

 ones dull, papillose. (Engelmann.) — In shallow depressions on the summit 

 Stone Mountain, Georgia (Engelmann, §-c.). 



I. Engelmanni, A. Braun, var. Georgiana, Engelm. Leaves 10'-12' 

 long, rather slender, stomatose ; spore-cases oval, with narrow velum ; larger 

 spores and smaller spores smooth. — Slow-flowing water in Horseleg Creek, 

 mountains of Georgia. 



I. Butleri, Engelm. Dioecious; trunk nearly globose; leaves 8-12, 

 bright green, S' - T long ; spore-cases usually oblong, spotted, the velum very 

 narrow, or none ; ligule subulate, from a triangular base ; larger spores 

 warty, smaller spores dark brown, papillose. (Engelmann.) — Barrens of Ten- 

 nessee [Dr. Gattinyer), and westward. 



