Perennial aquatic or ditch herbs, with alternate dissected or palmately lobed leaves, the segments of the submerged ones often filiform, and solitary rather small white flowers, borne on peduncles opposite the leaves. Sepals and petals usually 5. Petals oblong or oval, the base sometimes yellowish, the claw bearing a small pit. Stamens several or numerous. Achenes oblique, compressed, not margined, beakless or short-beaked, transversely wrinkled. [Greek, referring to the aquatic habitat.]

About 20 species of very wide geographic distribution. Besides the following, several others occur in western North America. Type species: Batrachium hederaceum (L.) S. F. Gray.

Leaves all dissected into filiform segments and lobes.

Leaves 1' - 2' long, flaccid, collapsing when taken from the water.

1.

B. trichophyllum.

Leaves 1' long or less, rigid when taken from the water.

2.

B. circinatum.

Leaves all reniform or broadly ovate, 3-5-lobed, 5"-10" wide.

3.

B. hederaceum.

21 Batr chium S F Gray Nat Arr Brit Pl 2 720 1821 269

1. Batrachium Trichophyllum (Chaix) F. Schultz. White Water-Crowfoot

Fig. 1927

Ranunculus trichophyllus Chaix in Vill. Hist. Pl. Dauph.

1; 335. 1786. Batrachium trichophyllum F. Schultz, Arch. Fl. France et All. 1: 107. 1848. Ranunculus aquatilis var. trichophyllus A. Gray, Man.

Ed. 5, 40. 1867. R. aquatilis var. caespitosus DC. Prodr. 1: 26. 1824. R. aquatilis capillaceus DC. Prodr. 1: 26. 1824.

Submerged; stems branching, usually 1° long or more. Leaves petioled, 1'-2' long, flaccid and collapsing when withdrawn from the water, repeatedly forked into capillary divisions; flowers white, 6"-9" broad, on stout peduncles 1'-2' long, blooming at the surface of the water; head of fruit globose, 2" broad; receptacle hairy; achenes apiculate.

In ponds and streams, Nova Scotia to British Columbia, south to North Carolina and California. Also in Europe and Asia. Consists, apparently, of numerous races, differing in habit, in size of flowers, number of stamens and shape of petals; several of these have been recognized as species. Water-milfoil. Green eel-grass. Pickerel-weed. June-Sept.

2. Batrachium Circinątum (Sibth.) Rchb. Stiff White Water-Crowfoot

Fig. 1928

Ranunculus circinatus Sibth.; J. E. Smith, Fl. Brit. 2: 596. 1800. Batrachium circinatum Rchb.; Spach, Hist. Veg. 7: 201. 1839. R. aquatilis var. divaricatus A. Gray, Man. Ed. 2, 7. 1856.

Similar to the preceding species, but the leaves are shorter, less than 1' long, spreading nearly at right angles from the stem, rigid when withdrawn from the water and sessile or nearly so; there appear to be no constant differences in flower or fruit.

In ponds and slow streams, Ontario, New England, northern New Jersey and Pennsylvania, and west to the Pacific Coast, extending south in the Rocky Mountains to Arizona. Also in Europe. Summer. Referred in our first edition to Batrachium divaricatum (Schrank) Wimmer.

Batrachium longiróstre (Godr.) F. Schultz, if distinct from this species, differs in having a longer beak to the achene.

2 Batrachium Circin Tum Sibth Rchb Stiff White Wat 2702 Batrachium Circin Tum Sibth Rchb Stiff White Wat 271

3. Batrachium Hederąceum (L.) S. F. Gray. Ivy-Leaved Crowfoot

Fig. 1929

Ranunculus hederaceus L. Sp. Pl. 556. 1753.

Batrachium hederaceum S. F. Gray, Nat. Arr. Brit. Pl. 2: 721. 1821.

Semi-aquatic, rooting extensively at the joints, branching, entirely glabrous. Leaves floating, or spreading on the mud, semi-circular, reniform or broadly ovate in outline, 3-5-lobed, 3"-6" long, 5"-10" broad, the lobes obtuse; flowers 2" - 3" broad; head of fruit globose, 2" wide; receptacle glabrous; achenes minutely beaked.

In ponds and pools, Newfoundland; southeastern Virginia and Maryland. Naturalized from Europe. June-