235 



Several forms occur in Brazil, distinguished mainly by the 

 length of the peduncle, the one regarded by Hegelm. as the type 

 with peduncles 3-5 mm. long, and fruit somewhat larger than 

 in ours. 



New York to Washington, D. C, west to Missouri, Ar- 

 kansas, Louisiana and Texas, Central and South America. 



2. C. margviata. Torr. Bot. Whip. Ex. 135(1856). Hegelm. 

 Verhand. Bot. Brand. 9, 12 (1867.) 



Amphibious, usually floating, sometimes growing in mud. 

 Submerged leaves linear, one-nerved, running gradually into the 

 emersed, which are oblanceolate or spatulate, and three-nerved, the 

 blade 4-6 mm. long and about 2 mm. broad. Styles as long as or 

 shorter than the fruit, reflexed, deciduous. Fruit i-i/{ ^^m- long 

 and 1^2-1^ mm. broad, with conspicuous membranous wings 

 and divergent lobes. 



Peculiar to the Pacific coast from Arizona to California. Also 

 attributed to Chili. 



3. C. Niittallii. Toriv Bot. Whip. Ex. 135 (1856). 



C . pediincidosa. Nutt. Trans. Am. Phil. Soc. Vol. V, n. s. 140 

 (1837) not Arnott nor C. pedunciilata, D.C. 



A small terrestrial species growing in moist grounds. Leaves 

 all spatulate, three- nerved, the blade 3 or 4 mm. long and i-i^ 

 mm. broad, often finely wrinkled or granulated, apparently with- 

 out stellate scales. Fruit thick, deeply emarginate at apex and 

 base, \-\ mm. in length and ^-i mm. in breadth, the lobes with 

 narrow marginal keels. Styles erect, longer than the fruit, decid- 

 uous. This and the following species are peculiar in bearing the 

 fruit on reflexed peduncles and burying it in the mud. 



First discovered by Nuttall in Arkansas and described by him 

 under the name C. pedtinctdosa, but, unfortunately, the name had 

 been already preoccupied.. It extends down the Mississippi to 

 Louisiana. (Hale, Langlois.) 



4. C. sepnlta. S. Watson. Proc. Am. Ac. 14, 298 (1879.) 



A small terrestrial prostrate species, similar in general ap- 

 pearance and habit to the preceding. Leaves linear, one-nerved, 

 3-5 mm. long, somewhat wrinkled or granulated below, as in 

 C. Niittallii, and apparently without stellate scale. Styles elongated, 

 reflexed, soon deciduous, Fruit thick, about y^ mm. long and 



