fruit ellipsoid, 1-3 mm. long, 2-4 mm. broad, the dorsal surface acute, narrowly 

 rounded to cuneate at the base, oblong in cross section, the acute dorsal and lateral 

 ribs distinct, the commissural surface constricted; oil-bearing cells conspicuous; 

 seed oblong-ovate in cross section. 



Along streams and low muddy ground or in shallow water in Okla. (Waterfall), 

 in Tex. in the Timber Belt, Coastal and Blackland Prairies and the Edwards Pla- 

 teau, N.M. (Eddy Co.) and Ariz. (Widespread), June-Aug.; from Mass., s. to Fla., 

 w. to Mo., Tex., s. Ut., N.M., Ariz., Calif., Mex. and W.I.; also in H.I. and 

 S. Afr. 



3. Hydrocotyle verticillata var. triradiata (A. Rich.) Fern. Fig. 574B. 



Similar in habit to var. verticillata; leaves to 6 cm. in diameter, 8- to 14-nerved, 

 shallowly 8- to 14-lobed; petioles slender, to 35 cm. long; inflorescence an axillary 

 interrupted simple or rarely branched spike to 22 cm. long, with few 4- to 15- 

 flowered verticils, the interverticillar distance to 4 cm., the flowers radiate, the 

 rays to 1 cm. long. H. Canbyi Coult. & Rose, H. australis Coult. & Rose. 



In open marshes and wet areas in Okla. (Cherokee Co.), in Tex. chiefly in the 

 Timber Belt, Coastal and Blackland prairies, Rio Grande Plains and Edwards 

 Plateau, w. to Ariz. (Santa Cruz, Pima, Yavapai and Mohave cos.), May-Aug.; 

 from Mass., s. to Fla., w. to Nev. and Calif., also Mex., C.A., W.I. and S.A.. 



4. Hydrocotyle bonariensis Lam. Sombrerillo. Fig. 573. 



Plants glabrous; stems slender, creeping; leaves orbicular to ovate-peltate, to 

 12 cm. in diameter, shallowly 12- to 19-lobed, the lobes crenate; petioles slender, 

 to 37 cm. long; peduncles exceeding the leaves; umbels proliferous, many-flowered; 

 rays to 2 cm. long, spreading and reflexed; involucral bracts lanceolate, acute; 

 flowers white to yellow; stylopodium depressed; fruit ellipsoid, 1-2 mm. long, 2-4 

 mm. broad, the dorsal surface acute, the acute dorsal and lateral ribs evident, the 

 commissural surface constricted. 



In sandbar ditches, wet depressions, along stream banks and in streams, in the 

 Tex. Coastal and Blackland prairies, and on the Gulf side of the Rio Grande 

 Plains, May-Nov.; from N.C., s. to s. S.A.; S. Afr. 



5. Hydrocotyle ranunculoides L.f. Fig. 575. 



Plants glabrous; stems slender to somewhat thickened, floating or creeping; 

 leaves roundish-reniform with a sinus at the base, not peltate, to 8 cm. long and 

 wide, 5- or 6-lobed about to the middle, the lobes crenate or lobulate; petioles 

 mostly slender, to 34.5 cm. long; peduncles shorter than the leaves, axillary; umbels 

 simple, 5- to 10-flowered; rays 1-3 mm. long, spreading and ascending; stylopodium 

 depressed; fruit suborbicular, 1-3 mm. long, 2-3 mm. broad, the dorsal surface 

 rounded, the ribs obsolete; strengthening cells absent. 



In shallow pools and muddy shores in Okla. {Waterfall), Tex. in the Timber Belt 

 and Blackland Prairies and Ariz. (Cochise, Pima and Santa Cruz cos.), Apr .-July; 

 from Pa. and Del., s. to Fla., w. to Ark. and Ariz.; also from Wash., s. along the 

 coast to Pan., Cuba and S.A. 



2. Centella L. 



A genus of perhaps 20 species, chiefly of the Southern Hemisphere. 

 1. Centella asiatica (L.) Urban. Fig. 573. 



Plant perennial from slender creeping rootstocks, with stems 1 to several dm. 

 long, rooting at nodes; leaves ovate-cordate to oblong, obtuse, to 10 cm. long and 

 9 cm. wide, entire or repand-toothed; petioles glabrous to fulvous-pubescent, 

 usually with a tuft of hairs at the apex, to 35 mm. long, usually much shorter; 

 inflorescence of simple lax to subcapitate umbels; peduncles axillary, shorter than 



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