MEMOIRS FEOM THE DEPARTMENT OP BOTANY OF COLUMBIA UNIVERSITY 29 



Stem 3-5 dip. higli, many-flowered; leaflets lanceolate (Mexican). 66. P. Pringlei. 

 Stem 1-2 dm. high, more or less leafy, several-flowered. 

 Flowers 8-15 mm. in diameter ; stem slender. 



Leaves deeply dissected ; sepals lanceolate. 67. P. Hooheriana. 



Leaves coarsely dentate ; sepals ovate-lanceolate. 68. P. nivea. 



Leaves dissected half way to the midrib. [57. P. quinquefolia.] 



Flowers 20-30 mm. in diameter ; stem stout. 69. P. villosa. 

 Stem less than 1 dm. high, subscapose, 1-3-flowered. 



Plant not yellowish hairy ; bractlets oblong or lanceolate. 70. P. uniflora. 

 Plant covered with yellowish villous hairs; bractlets broadly ovate or elliptical. 71. P. VaJdiana. 



§ 15. MULTIFIDAE. 



Mostly decumbent or ascending perennials (P. Pennsylvanica and P. bipinnatifida 

 however erect). Leaves pinnate, of 2-7 pairs of incised or dissected leaflets, more or less 

 tomentose beneath. Petals yellow, obovate, slightly if at all emarginate, generally not 

 exceeding the sepals. Style very short, in all our species except P. multifida, thickened 

 and glandular at the base. 



The larger species resemble somewhat the Leucophyllae, and the smaller ones, the 

 Rubricaules, but differ from both groups by the short and thick style. Through P. 

 pulchella and P. pseudosericea the group connects with the Niveae. 



Pubescence not silvery-white. 



Stem decumbent or ascending ; leaflets 2-3 rather approximate pairs. 



Terminal leaflet stalked ; plant 5 cm. high or less. 72. P. Sommerfeltii. 



Terminal leaflet sessile. 



Stem silky-villous with yellowish hairs. 73. P. pulchella. 



Stem slightly silky-strigose. 



Segments of the leaves obtuse ; style thickened at the base. 74. P. litoralis. 

 Segments of the leaves acute ; style not thickened. 75. P. multifida. 



Stem erect ; leaflets 3-7, usually rather remote pairs. 



Stem glabrate, or merely puberulent. 76. P. glabrella. 



Stem more or less hirsute. 



Plant dark green ; leaves scarcely paler beneath. 77. P. atrovirens. 



Plant not dark green, leaves decidedly paler beneath. 78. P. Penmylvanica. 



Pubescence silvery-white on one or both sides of the leaves. 



Stem decumbent or ascending, ^1 dm. high. 79. P. pseudosericea. 



Stem erect, 3-5 dm. high. 80. P. bipinnatifida. 



