Part 4, 1908] ROSACEAE 323 
XVIII. Rubrae. Perennial plants, with erect stems, 3 dm. high or more. Petals 
dark-red or dark-purple, broadly obcordate, rather large and showy. Stamens mostly 20, 
in 3 series on the thick and swollen, red or purple margin of the disk, the antisepalous sta- 
mens generally larger and with thicker filaments. 
74. Potentilla madrensis Rose, Contr. U. S. Nat. Herb. 
8: 30. 1903. 
Perennial, with a thick root and very short caudex; stems several, 2-4 dm. high, erect 
or ascending, glabrous below, somewhat villous and meade -pubescent above; leaves 
mostly basal ; petioles 2-7 cm. long; leaflets 3, obovate to oblong, 2-2.5 cm. long, crenate, 
rounded at the apex, glabrous and green on both sides; stem-leaves similar but small and 
. Short-petioled; blades about 1 cm. long; stipules lanceolate, entire, 5 mm. or less long; 
flowers few, on almost erect branches; bractlets linear, about 2 mm. long; sepals ovate, 
acute, 3-4 mm. long; petals purplish, obcordate, 5-6 mm. long. 
TYPE LOCALITY: Santa Gertrudis, Tepic. 
DISTRIBUTION : Known only from the type ar iek 
ILLUSTRATION : Contr. U.S. Nat. Herb. 8: pl. 2. 
75. Potentilla Thurberi A. Gray, Mem. Am. Acad. 
II. 5: 318. 1854. 
Perennial, with a woody tap-root and short caudex; stem ascending, 3-7 dm. high, 
finely pubescent and sparingly villous ; stipules large, 1-2 cm. long, broadly ovate, coarsely 
toothed ; basal leaves and lower stem-leaves long-petioled, digitately 5-7-foliolate, glabrate 
or slightly silky, sometimes glandular-puberulent, thin, sometimes slightly paler beneath 
but not tomentose; leaflets obovate, 3-5-cm. long, coarsely toothed with broad teeth, 
almost crenate; upper stem-leaves sessile, 3-5-foliolate with oblong leaflets; cyme open 
and branched ; flowers about 15 mm. in diameter ; hypanthium puberulent, in fruit about 
1 cm. in diameter; bractlets 5-6 mm. long, lanceolate, about equaling the triangular acute 
sepals; petals nearly orbicular, emarginate, exceeding the sepals, dark reddish-purple, 
7-10 mm. long; stamens 20-30, the inner 5 with thicker filaments, borne on aring-like thick- 
ening of the disk; pistils numerous. 
TYPE LOCALITY: Near Santa Rita del Cobre, [New Mexico]. 
DISTRIBUTION : Mountains of New Mexico, Arizona, southern California, and northern Mexico. 
ILLUSTRATION: Mem. Dep. Bot. Columbia Univ. 2: pi. 2. 
76. Potentilla atrorubens Rydb. Bull. Torrey Club 24: 11. 1897. 
Potentilla Thurberi Rothr. Bot. Wheeler Surv. 113. 1878. Not P. Thurbert A. Gray. 1854. 
_ Perennial, with a woody tap-root and a short caudex; stem 4-7 dm. high, finely pubes- 
cent and with scattered long villous spreading or reflexed hairs; stipules ovate or lanceo- 
late, 1-2 em. long, often toothed; basal leaves and lower stem-leaves long-petioled, dig- 
itately 5-7-foliolate, glabrous or slightly silky above, silky and white-tomentose beneath ; 
petioles with long spreading hairs; leaflets obovate to oblanceolate, coarsely serrate, 2-5 
cm. long; stem-leaves sessile, 3-5- soliolates cyme open and branched; flowers about 15 
mm. in diameter; hypanthium silky-villous and finely pubescent, about 1 cm. in diameter ; 
bractlets lanceolate, 6-8 mm. long, often equaling the lanceolate-triangular, more or ies 
acuminate sepals; petals dark reddish-purple, very broadly obcordate, exceeding the 
sepals, 7-10 mm. long; stamens 20. 
TYPE LOCALITY: [Mt. Graham,] Arizona. 
DISTRIBUTION: Mountains of Arizona, New Mexico, and northern Mexico. 
ILLUSTRATIONS : Bull. Torrey Club 24: pl. 288 ; Mem. Dep. Bot. Columbia Univ. 2: pi. J 
77, Potentilla rubra Willd. ; Schlecht. Ges. Nat. Freunde Berlin 
Mag. 7: 272. 1815. 
Potentilla comaroides Humb. & Bonpl.; Nestler, Monog. Potent. 62. 1816. 
Perennial, with a thick tap-root and short caudex; stems ascending or decumbent, 2-3 
dm. high, few-flowered and few-leaved, silky-canescent ; basal leaves appressed-pilose or 
