533 



ELATINACEAE. 



VOL. II. 



hypogynous. Stamens the same number or twice as many. Ovary 2-5-celled; 

 styles 25, stigmatic at the apex; ovules oo, anatropous. Capsule with septicidal 

 dehiscence. Placentae central. Seed-coat crustaceous, rugose or ribbed. 



About 30 species, of wide geographic distribution. 



Flowers 2-4-merous ; glabrous aquatic or creeping herbs. i. Elatine. 



Flowers mainly s-merous ; pubescent ascending or diffuse herbs. . 2. Bergia. 



i. ELATINE L. Sp. PI. 367. 1753. 



Small glabrous or glabrate aquatic or creeping herbs, with opposite or verticillate leaves, 

 and minute axillary mainly solitary flowers. Sepals 2-4, persistent, membranous, not ribbed. 

 Petals of the same number, hypogynous. Stamens of the same number or twice as many. 

 Styles or stigmas 2-4. Pod membranous, globose, 2-4-valved. Seeds o, straight, or slightly 

 curved, striate longitudinally and transversely. [Greek, fir-like, with reference to the leaves.] 



About 10 species, natives of temperate and warm regions. In addition to the following, another 

 occurs in California and one in Montana. Type species : Elatine Hydropiper L. 



Petals and stamens 2 ; seeds distinctly sculptured. 



Leaves obovate ; seeds with 9-10 longitudinal and 20-30 transverse striae, i. E.americana. 



Leaves oblong or oval ; seeds with 6-7 longitudinal and 10-12 transverse striae. 



2. E. brachyspcrma. 

 Petals and stamens mostly 3 ; seeds little sculptured. 3. E. triandra. 



i. Elatine americana (Pursh) Arn. Water-wort. Mud-purslane. Fig. 2905. 



Peplis americana Pursh, Fl. Am. Sept. 238. 1814. 

 Elatine americana Arn. Edinb. Journ. Sci. i : 430. 1830. 



Erect or spreading, tufted, aquatic or terrestrial, i'-ii' long 

 often submerged. Leaves obovate, obtuse, i"-3" long, i' 

 wide or less ; flowers sessile, axillary, minute, rarely opening 

 in the submerged forms; sepals, petals, stamens and stigmas 2 

 (rarely 3 in the terrestrial forms) ; capsule globose, nearly \" 

 in diameter; seeds \" to nearly \" long, slightly curved, marked 

 by 9-10 longitudinal striae and 20-30 cross-bars. 



Margins of ponds and slow streams, Quebec to British Colum- 

 bia, Virginia, Missouri, Texas and Mexico. Summer. 



2906. 



2. Elatine brachysperma A. Gray. Short-seeded Water-wort. 



Elatine brachysperma A. Gray, Proc. Am. Acad. 13: 361. 1878. 



Terrestrial or sometimes submerged, spreading, tufted, 1-2' long. 

 Leaves oblong, oval or lanceolate, narrowed at the base, 2"-$" long, 

 about i" wide, obtuse ; flowers sessile, axillary, minute ; sepals, petals, 

 stamens and stigmas mainly 2; capsule nearly as in the preceding 

 species ; seeds short-oblong, nearly straight, about \" long, marked 

 by 6-7 longitudinal striae and 10-12 cross-bars. 



Margins of ponds, Illinois and California, doubtless occurring between 

 these limits. Summer. 



3. Elatine triandra Schk. Long-stemmed 

 Water-wort. Fig. 2907. 



Elatine triandra Schk. Bot. Hand, i: 345. 1791. 



Flaccid, tufted, immersed or creeping, stems 2'-4' 

 long, much branched. Leaves oblong or oblanceo- 

 late, very thin, obtuse, 2" -4" long, i" wide, narrowed 

 at the base; flowers minute, axillary, sessile; sepals 

 commonly 2 ; petals, stamens and stigmas 3 ; seeds 

 slightly curved, about the size of those of E. ameri- 

 cana, slightly marked longitudinally and transversely. 



Ponds, Illinois, South Dakota and Nebraska to Wash- 

 ington. Also in Europe. Summer. 



