460 MINNESOTA BOTANICAL STUDIES. 
BATRACHIUM 8S. F. Gray, Nat. Arr. Brit. Pl 2: 720: 
1821. 
(Name from the Greek, in allusion to the aquatic habitat of 
the plants.) 
Aquatic, or semi-aquatic perennial herbs; leaves dissected or 
lobed, submerged ones usually with filiform segments; petioles 
with stipular-dilated membranous bases: flowers solitary, op- 
posite the leaves, rather small, white; sepals usually 5; petals 
usually 5, base often yellowish; claw with a naked nectar pit; 
stamens several or many: ovules oblique, compressed, not 
margined, nearly beakless, transversely rugose. About 20 
species, mostly of north temperate regions of the world. The 
following are all that are found in North America. Section 
BatTracuium DC. Syst. 1: 233, under Ranunculus. 
Key To SPECIES. 
A. Aquatic leaves with filiform segments present; receptacle hairy. 
B. Leaves all sessile or nearly s0............20..00000 1. divaricatum. 
BB. Leaves, except the upper ones long-petioled. 
C. Emersed leaves always present, with segments broader than 
RAT aa sitemap tence roen te eee sonemacnetunekiee eens Oaeeces 2. aguatile. 
CC. Emersed leaves if present only fleshy or nearly linear. 
3. trichophyllum. 
AA. Aquatic leaves none, or few, and with few divisions; receptacle 
glabrous. 
B. Styles minute, shorter than the ovaries............ 4. hederaceum. 
Bete by les LOMO aise LILO 5 soso to: niente cigs tan ase one eee 5. Lobbze. 
1. B. divaricatum Wino. Fl. Schles. 10. 1841. 
Feanunculus aguatilis 8. LINN. Sp. Pl. 556. 1753. 
FR. divaricatus SCHRANK, Baier. Fl. 2: 104. 1789. 
F. circinatus SiBTH. Fl. Oxon. 175. 1794. 
FP. aquatilus var. stagnatalis DC. Prod. 1: 27. 1824. 
Batrachium circinatum Spacu. Hist. Veg.'7: 201. 1839. 
fe. stagnatalis WALLR. Sched. Crit. 285. 1848. 
FP. aquatilis var. divaritcatus GRAy, Man. 2 ed. 7. 1856. 
L. longirostris GopRON, Ess. 32. f. 9. 1862. 
Fe. aguatilis var. longtrostris Lawson, Rev. Canad. 
Ranune. 43. 1870. 
Leaves sessile to the dilated stipule-like base, dissected into 
rigid lobes spreading at right angles to the stem, not collapsing 
when taken from the water; no floating nor emersed leaves: 
