xn. 



Small plants floating on the water. Rhizome elongate, provided with 

 a single central stele. Leaves folded in the bud, simple or deeply 2-lobed. 

 Fertile leaves or segments metamorphosed into globose or ellipsoidal, 

 unilocular sporocarps; spores of 2 kinds, macrospores and microspores 

 borne in separate sporocarps. 



Idanson. 



Sporocarps borne on the basal segment of the water-leaves, provided 

 with a central, columnar placenta bearing the sporangia; microsporangia 

 long-stalked, the stalk consisting of 1 row of cells; macrospores provided 

 at the apex with 3 free lobes ; microspores gathered together in a single mass. 



Leaves borne in whorls of 3, of which 2 are normal, simple, floating 

 leaves, and the 3rd, lower one (water-leaf), is metamorphosed into many 

 long, root-like segments to replace the roots, which are wanting. Engl. 

 & Prantl, Nat. Pfl.Fam., I 4 , fig. 210 AB. 



Chiefly tropical. 



(1) S. iiataiis. Ao/fm., Bk., Fern All., 135; CopeL, Philipp. Journ., 

 IV C , 14; Corda, Rhizos., tab. II, fig. 111; verticiUata, Rb., Calc. Journ., 

 1845, tab. XVIII XX; Griff., Icon., II, tab, CXXHI CXXVIH ; S. Spren- 

 gdii, Corda, 1. c., tab. II, fig. 1223. 



Rhizome brownish-pubescent. Leaves horizontal or nearly so, oblong, 

 9 12V 2 mm. long, about J 2 as broad, rounded at both. ends or cordate at 

 the base; upper surface bright-green; veins oblique, 15 20 on each side 

 of the costa, each with 6 8 tufts of minute bristles on the upper side; 

 under surface brownish-pubescent. Sporocarps 4 8 in a cluster. 



Java (abundant); Br. India, China, Japan, North Asia, Europe. 



