302 EANUNCULACEiE. 



uumerous, minute, on filiform pedicels: achenes rather few, in a g-lobose 

 head, rounded and flattened, papillose and short-hairy, the beak very 

 short, the small tip abruptly recurved. Var. pnsillns, B. & W. Bot. Calif, 

 i. 9; Greene, Bull. Torr. Club, xiv. 116. Annual, very slender, usually 

 reclining; organs of the fi. few and definite (4 or 5 only in each circle). 

 The type is perennial, extending from the foothills of the Sierra near 

 Chico southward to the southern seaboard. In the Bay region we have 

 only the variety. It is common in the hilly districts from Napa Co. to 

 San Mateo, in the shade of oaks, and along streams. Apr., May. 



20. R. MURiCATUs, Linn. Sp. PI. i. 55.5 (1753). A stoutish and glabrous 

 annual with yellow-green herbage, and round-reniform slightly lobed 

 leaves: fl. small and inconspicuous: achenes very large, with stout ensi- 

 form beak and coarsely muricate-prickly sides. — Common about San 

 Francisco, at the Presidio, Mountain Lake, and in the Mission Hills, in 

 wet sandy soil, or about springs; also in Marin Co. ; doubtless naturalized 

 from Europe; flowering at all seasons. 



21. R. delphiiiifolius, Torr.; Eaton, Man. 2 ed. 395 (1818), not HBK. 



(1821); Britt. Bull. Torr. Club, xviii. 363: R. lacustris, Beck & Tracy, 

 Eaton, Man. 3 ed. 895 (1822); Greene, Pitt. ii. 62: R. multifidus, Pursh 

 (1814), not Forsk. (1775): R. Purshii, Hook. (1829). Perennial, aquatic; 

 stems a few inches to several feet long, mostly submersed, as are also 

 most of the leaves, these all divided into numerous linear-filiform seg- 

 ments: fl. (and some of the uppermost leaves) emersed and almost 

 floating, 1 in. broad, yellow: sepals spreading: petals 5, broadly obovate: 

 achenes slightly flattened, the sides faintly rugose, the basal part corky- 

 thickened, the rather long and slender beak straight or somewhat 

 incurved. — In mountain lakes; Humboldt Co., C'hesnut cfc Dreiv. A hand- 

 some aquatic, more common on the Atlantic side of the continent than 

 with us. Late in the season it may be found in a terrestrial form, with 

 leaves less finely dissected. June, July. 



* * Aquatics, with leaves mostly capillaceous-muUifid and submersed; pe- 

 duncles opposite the leaves, recurved in fruit; petals white, ivith naked 

 nectariferous pit; achenes Utile compressed, transversely rugose- 

 striate. — Genus Batrachium, S. F. Gray; Wimmer; Fries. 



22. R. aquatilis, Dod. Pempt. 576 (1583); Ray, Syn. 3 ed. 249 (1724); 

 Linn. Sp. PI. i. 556 (1753). Perennial, the emersed and floating leaves 

 when present, roundish, 3-lobed: sepals deciduous: styles subulate: 

 achenes slightly rugose, usually hispidulous, 12—20 in a rather compact 

 globose head. — Frequent in ponds and ditches, sometimes in running 

 streams, or, on muddy shores appearing in a dwarf and wholly terrestrial 

 form. The Old World type, with round-reniform emersed foliage, and 

 hispidiilous achenes, not known in eastern America, has been found in 



