MEMOIRS FROM THE DEPARTMENT OF BOTANY OF COLUMBIA UNIVERSITY 21 
cies, must naturally be more or less artificial. In many cases the species are very closely 
related, without many well-marked distinguishing characters and the differences are 
brought out better in the general description than can be done in the artificial key. 
KEY TO THE GROUPS. 
Flowers dark red or dark purple. 
Flowers yellow or whitish. 
Flowers solitary, axillary, on long pedicels. 
Flowers many in very leafy cymes. 
Bractlets 3-toothed. 
Bractlets entire. 
Annuals or biennials or short-lived perennials ; style fusiform. 
Perennials ; style filiform but short. 
Flowers cymose, but cymes not very leafy, generally rather few-flowered. 
Leaves digitately 5—9-foliolate. 
Plants less than 2 din. high. 
Leaves tomentose, at least beneath. 
Leaves not tomentose. 
Stem spreading, with many branches ; sepals and bractlets in- 
curved in fruit. 
Stem simple, erect, few-flowered ; sepals and bractlets not in- 
curved. 
Plants more than 2 din. high. 
Leaves digitately 5-foliolate with an additional pair of smaller leaflets on 
the petiole or with the middle leaflet petiolate. 
Leaves digitately 3-foholate. 
Sepals 3-toothed ; petals white. 
Sepals entire ; petals yellow. 
Leaves not tomentose. 
Leaflets merely toothed. 
Leaflets divided to near the base into 2-3 entire segments. 
Leaves more or less tomentose beneath. 
Leaves pinnate. 
Style not longer than the mature achene, thickened and glandular be- 
low (except in P. multifida) ; leaves usually more or less tomen- 
tose beneath. 
Style much longer than the mature achene, filiform. 
Leaves with 1-3 more or less approximate pairs of leaflets. 
Leaves more or less tomentose beneath. 
~ 
Lae 
12: 
. Biflorae. 
14. 
2 
0 
Haematochri. 
Tormentillae. 
Heterosepalae. 
. Supinae. 
Argenteae. 
Conecinnae. 
. Subviscosae. 
. Aureae. 
Graciles. 
. Subjugae. 
Ovales. 
Frigadae. 
Niveae. 
15. Multifidae. 
16. Rubricaules. 
