XI. 



Aquatic or subaquatic. Rhizome slender, creeping in the mud, pro- 

 vided with a single, central, tubular stele. Leaves without blade, or with 

 blades floating on the surface of the water or rising above it, circinate 

 in vernation. Fertile leaves or segments metamorphosed into bi- or 

 plurilocular, globose, ellipsoidal, pyriform or bean-shaped, sessile or stalked 

 sporocarps placed at the base of the petioles of the normal (barren) leaves, 

 often close to the rhizome, containing spores of 2 kinds, both macrospores 

 and microspores borne in the same sporocarp. 



OO. M^JEfcSILEA., Linne. 



Sporocarps bilateral, round, oblong, quadrate or bean-shaped, 2-valved, 

 plurilocular, horizontally veined, the locules (sori) oblong-cylindrical, hori- 

 zontally arranged in 2 close vertical rows on a mucilaginous placental 

 cord, the veins forked, with the fork-branches whether or not anastomosing, 

 the base provided with 2 teeth. 



Rhizome wide-creeping, the leaves produced singly or in tufts from 

 its nodes. Barren leaves long-stalked, 4-foliate ; leaflets cruciate, cuneate, 

 with the outer edge truncate or rounded, whether or not provided with 

 translucent or yellow-brown, longitudinal spurious veinlets (streaks) between 

 the true ones. Engl. & Prantl, Nat. Pfl.Fam., I 4 , fig. 225 A. (Marsilia). 



Tropical, subtropical, and in temperate countries. 



Arrangement of the sections. 



1. EUMARSILEA. Fork branches of the veins of the sporocarps not 



anastomosing, or anastomosing near the apex only. - - Engl. & 



Prantl, 1. c., fig. 225 B. 

 2. ZALUSIANSKAYA. Fork branches of the veins of the sporocarps 



anastomosing from the base. Engl. & Prantl, 1. c., fig. 225 D. 



(Not in Malaya). 



