BUTTERCUP FAMILY 85 



lobed and cleft into oblong or linear divisions. Flowers about 1 in. 

 in diameter. Petals 5-7, yellow, spatulate-oblong of obovate. Akenes 

 hardly margined, beak slender, straight or slightly curved. On hill- 

 sides or in woods or prairies. 



5. R. septentrionalis Poir. Marsh Buttercup. Stems smooth or 

 slightly hairy, erect, or in wet ground often forming long runners. 

 Leaves 3-divided, on long petioles, the divisions stalked, cleft or lobed, 

 and wedge-shaped. Petals yellow, obovate, twice as long as the 

 sepals. Akenes flat, strongly margined, beak stout and nearly straight. 

 In moist soil. 



6. R. hispidus Michx. Reclining Buttercup. Perennial. Stems 

 ascending or spreading, densely soft-hairy when young, few-leaved. 

 Leaves pinnately 3-5-divided, with sharply, cleft divisions. Flowers 

 ^1^ in. in diameter. Petals about twice as long as the spreading 

 sepals. Head of fruit globose or nearly so. Akenes broadly oval, 

 lens-shaped, with a narrow margin. In dry woods and thickets. 



7. R. pennsylvanicus L. f . Upright Buttercup. Perennial. Stems 

 rough-hairy, erect, 2-3 ft. high. Leaves compound in threes, on long 

 and very hairy petioles ; leaflets long-stalked, 3-parted, the divisions 

 ■sharply lobed or toothed. Flowers small. Petals yellow, shorter than 

 the sepals. Akenes flat, smooth, in oblong heads ; beak broad and 

 straight. On low ground.* 



8. R. bulbosus L. Bulbous Buttercup, Early Buttercup. 

 Stem upright, from a solid bulb about as large as a filbert, about 

 1 ft. high, hairy. Basal leaves 3-divided, the divisions lobed and 

 cleft. Peduncles furrowed. Flowers large and showy (^1 in. in 

 diameter). Sepals strongly reflexed. Petals roundish, wedge-shaped 

 at the base. Akenes with a very short beak. Naturalized from 

 Europe. Common in grass fields in New England. 



9. R. acris L. Tall Buttercup. Erect, hairy, 2-3 ft. high. 

 Leaves 3-7-parted, the divisions of the lower ones wedge-shaped, 

 deeply cut and lobed. Peduncles not furrowed. Sepals spreading, 

 downy. Petals obovate, a little smaller and paler yellow than in 

 No. 8. A common weed, naturalized from Europe, in grass fields 

 and elsewhere, especially eastward. 



n. THALICTRUM L. 



Erect perennial herbs. Leaves compound, with stipules. 

 Flowers in panicles or racemes, often somewhat monoecious 

 or dioecious, wind-fertilized. Sepals 4-5, petal-like. Petals 

 none. Stamens many. Carpels few or many ; ovule 1. Fruit 

 a small head of akenes. [The following species are both 

 usually dioecious.] 



