RA NUNCULA CEA E. 429 



Leaves all reniform, 3-5-lobed, about i cm. wide: receptacle glabrous. 



i. B. hederaceum. 

 Leaves all dissected into filiform segments; receptacle hairy. 



Leaves sessile, circinate, the segments short, spreading around the stem nearly in 



one plane ; beak of achene minute. 2. B. divaricatum, 



Leaves more or less petioled, not circinate. 



Beak of achene nearly i mm. long. 3. ft. longirostris. 



Beak of achene minute or none. 



Petals 5-7 mm. long, broadly obovate ; stamens many. 



Segments of the leaves 10-15 nim. long, rather rigid, scarcely collaps- 

 ing when withdrawn from water. 4. B. trichophyllum. 

 Segments of the leaves 15-30 mm. long, flaccid, collapsing when with- 

 drawn from water. 5. B. flaccidum. 

 Petals less than 5 mm. long, oblong-obovate, stamens 5-12. 



Stem slender ; leaves not very flaccid. 6. B, Drouetii. 



Stem filiform; leaves very flaccid. 7. B. confervoides. 



1. Batrachium hederaceum (L. ) S. F. Gray. IVY-LEAVED CROWFOOT. 

 (I. Ff. 1628.) Semi-aquatic, rooting extensively at the joints, branching, entirely 

 glabrous. Leaves floating, or spreading on the mud, the lobes obtuse; flowers 

 white, 4-6 mm. broad; head of fruit globose, 4 mm. wide; achenes rugose, mi- 

 nutely beaked. In ponds and pools, Newf. and southeastern Va. Nat. from 

 Europe. June-Aug. 



2. Batrachium divaricatum (Schrank) Wimm. CIRCINATE WHITE WATER- 

 CROWFOOT. (I. F. f. 1627.) Submerged, 3 dm. or more. Leaves distant, 1-2 

 cm. broad, with very short lobes; stipules membranaceous, very short and broad, gla- 

 brate; peduncles 4-10 cm. long; petals broadly obovate, about 5 mm. long; head 

 of fruit globose. Very rare; most specimens referred here belong to the next. 

 Lakes and ponds, N. Eng. to Minn. Also in Europe. June-Aug. 



3. Batrachium longirostris (Godr.) F. Schultz. LONG-BEAKED WHITE 

 WATER-CROWFOOT. Stem very leafy, submerged. Petioles short; stipules broad 

 and hairy; segments very numerous, about 15 mm. long, not flaccid; peduncles 

 2-4 cm. long; petals broadly ovate, 5-7 mm. long; head globose. Has been 

 confused with the preceding. In ponds and streams, Ont. and N. Eng. to Minn., 

 N. Mex. and Mo. June-Aug. 



4. Batrachium trichophyllum (Chaix) Bossch. WHITEWATER-CROWFOOT. 

 (I. F. f. 1626.) Submerged; stems usually 3 dm. long or more. Leaves petioled, 

 3-5 cm. long, stipules broad and short, hairy; flowers white, 12-18 mm. broad, 

 on stout peduncles 2-5 cm. long, blooming at the surface of the water; head 

 of fruit globose, 4mm. broad; receptacle hairy; achenes apiculate but beakless. 

 In ponds and streams, N. S. to Br. Col., south to N. Car. and Cal. Also in Europe 

 and Asia. The so-called var. caespitosus is a small mud form with rather fleshy 

 leaf-segments. June-Sept. 



5. Batrachium flaccidum (Pers. ) Rupr. FLACCID WHITE WATER-CROWFOOT. 

 Like the next preceding except the leaves, which have longer, more slender petioles 

 and very long flaccid leaf-segments, collapsing when withdrawn from water. In 

 streams, Mass, to Wash., south to N. Car. and Lower Cal. Also in Europe, Asia 

 and South Africa. May-Sept. 



6. Batrachium Drouetii (F. Schultz) Nym. DROUET'S WHITEWATER-CROW- 

 FOOT. Like B. trichophyllum. but more slender and with smaller flowers, fewer and 

 more slender leaf-segments, narrower and glabrous stipules and fewer stamens. In 

 streams, Vt. and R. I. to Alaska, south to Lower Cal. Also in Europe, Asia, 

 Africa, and Bolivia. 



7. Batrachium confervoides Fries. FILIFORM WHITE WATER-CROWFOOT. 

 Resembling the last, but stem filiform, 1-2 dm. long; leaves very flaccid and the 

 receptacles conic, not ovoid. In cold pools, from Lake Winnipeg (according to 

 Hiern) to Alaska, and south to the Yellowstone Park. Also northern Europe. 



24. FICARIA Huds. 



Glabrous slightly fleshy perennial herbs, with thickened tuberous roots, 

 branched or simple spreading or erect stems, petioled entire or toothed cordate 

 leaves, and large solitary yellow terminal or axillary flowers. Sepals 3 or some- 

 times 5, deciduous. Petals 7-12 (commonly 8). yellow, or red at the base, bearing 



