MEMOIRS FROM THE DEPARTMENT OF BOTANY OF COLUMBIA UNIVERSITY 145 
Potentilla unguiculata Greene, Fl. Fran. 1: 68. Mainly. 1891. 
ILLUSTRATIONS: Pate 85, f- 1; dissection of flower, f. 2; pistil, f. 3; stamen, Ties 
fruiting hypanthium and ealyx, f. 5. 
Root very thick, crowned with a short rootstock covered with brownish, densely 
yellowish-hairy scales. Stems several, 3-4 dm. high, erect or ascending, branched, silky- 
villous and rather leafy. Stipules lanceolate, 1-2 dm. long, often pectinately cleft. Basal 
leaves numerous, 1-2 dm. long, densely white-silky, pinnate; leaflets numerous, gen- 
erally over 30, crowded and more or less imbricated : petioles and lower part of the 
stem silky-villous with long and reflexed hairs; leaflets .5-1 em. long, divided to the base 
into oblong segments. Cyme much branched, many-flowered, at first rather dense, in age 
open, more or less flat-topped. Hypanthium cup-shaped or campanulate, 8-5 mm. in di- 
ameter; bractlets oblong or lanceolate, about a third shorter than the ovate-lanceolate or 
triangular sepals. Petals white, broadly obovate, clawed, much exceeding the sepals. 
This species was described by Brewer and Watson in the Botany of California under 
the name IJvesia wnguiculata and has since gone under that name. It is evidently very 
distinct from the original I. wnguwiculata of Gray. It is much nearer related to H. Pick- 
eringit from which it differs mainly in the more robust habit, white petals and slightly 
longer pedicels. It is a native of the Sierra Nevada of Central California. Speci- 
mens examined : 
California, J. G. Lemmon, Nos. 11, 12 and 71, 1874; No. 95, 1875; C. F. Sonne, 
Nos. 6 and 353, 1886; 'T. S. Brandegee, 1887. 
33. Horkelia Pickeringii (Gray). 
Ivesia Pickeringii Gray, Proc. Am. Acad. 6: 531. 1865. 
Torr. Bot. U. 8. Expl. Exp. 288; Wats. King’s Rep. 5: 448; Brewer & Wats. Bot. 
Cal. 1: 182; Torr. & Gray in Newberry, Pac. R. R. 6°: 72 (name only); Rattan, An. 
Key W. Coast Bot. 52; Howell, Fl. N. W. Am. 1: 181. 
Potentilla Pickeringii Greene, Pittonia, 1: 105. 1887. 
Greene, Fl. Fran. 1: 68. 
Iuuusrrations: Bot. U. 8. Expl. Exp. pl. 4 Puate 86, jf. 41-2; dissection of 
flower, f. 3; stamen, f. 4; pistil, f. 5; fruiting hypanthium and calyx, f. 6. 
Root deep and thick, crowned by a short erect rootstock covered with brown hairy 
scales. Stems erect and ascending, 2-4 dm. high, finely villous, more or less leafy, di- 
chotomously branched. Stipules lanceolate. Leaves numerous, grayish or white silky- 
villous, pinnate with very numerous, crowded and somewhat imbricated leaflets, these 
