120 MEMOIRS FROM THE DEPARTMENT OF BOTANY OF COLUMBIA UNIVERSITY 
lated to the achene and at last deciduous. Ovule and seed inserted near the base of the 
style, pendulous and anatropous. 
The genus consists of about 50 species, all natives of western North America. They 
are all perennials, with a thick woody caudex or rootstock covered with brown scales. 
The leaves are always pinnate and generally with rather numerous leaflets. In [vesia 
they are usually crowded and more or less overlapping. In H. pygmaca, H. Shockleyt, 
H. Baileyi and H. saxosa, the flowers much resembles those of Sibbaldias, from which these 
species are easily distinguished by their terminal style and pinnate leaves. The last 
species apparently forms a transition to Potentilla. 
KEY TO THE GROUPS. 
Filaments dilated, petaloid. 
Stamens 10. Sub-genus EUHORKELIA. 
Lower stipules not dissected into linear filiform segments. 
Cyme very leafy; hpyanthium campanulate;’ bractlets ovate, much exceeding the sepals 
and petals. 1. Californicae. 
Cyme less leafy; calyx cupulate or saucer-shaped;! bractlets not exceeding the sepals. 
Leaves with 4-15 pairs of toothed or dissected leaflets. 
Inflorescence truly cymose; filaments uniform. 
Cyme many- or seyeral-flowered; bractlets ovate or lanceolate; leaflets not 
crowded. 2. Cuneatae. 
Cyme few-flowered; bractlets linear; leaflets crowded and imbricated, silvery 
white. 6. Sericatae. 
Cyme sub-capitate or fastigiate-corymbose; outer filaments triangular, Inner ones 
oblong-lanceolate; bractlets linear. 3. Capitatae. 
Leaves of 2-4 pairs of leaflets, which are 2-3-( seldom 5-) toothed only at the apex. 
4, Tridentatae. 
Lower stipules dissected into linear-filiform hairy segments. 5. Hirsutae. 
Stamens 20. 
Pistils numerous; hypanthium campanulate; sepals reflected in anthesis. 
Subgenus HorKELIELLA. 
Pistils 3-6; hypanthium turbinate. CH. argyrocoma in IvEsIA. ) 
Filaments filiform. Subgenus Ivesra. 
Leaflets numerous, more or less crowded, often imbricated, generally divided to near the base. 
Stem leafy (less so in J. campestris) ; stamens 15-20. 
Cyme corymbiform or subcapitate; petals obovate with a long claw. 8. Unguiculatae. 
Cyme generally open with lax branches; petals with very short claw if any, white. 
9. Hrenicae. 
1In the description of the hypanthium in this genus the term campanulate is used when the depth equals or excels the 
diameter; cupulate or cup-shaped when it equals about one-half of the diameter; saucer-shaped when it is equal to one-third of 
the diameter or less; wheel-shaped when it is flat or nearly so. 
