254 NORTH AMERICAN FLORA [VoLUME 22 
like; inflorescences short, 1-4 cm. long, dense, usually simple; pedicels 1-2 mm. long; 
hypanthium hemispheric, 1 mm. deep, densely silky; sepals ovate-lanceolate, acute, 1.5 
mm. long; petals spatulate, obtuse, 1.5 mm. long; follicles 3-5, 2 mm. long, 2-3-ovuled, 
1-2-seeded. 
TYPE LOCALITY: On high shelving rdcks, in the Rocky Mountains, towards the sources of the 
Platte. 
DISTRIBUTION : On rocks, from the Black Hills of South Dakota to New Mexico, Arizona, Cali- 
fornia, and Montana. 
ILLUSTRATION : Bot. Gaz. 15: pl. 14. 
5. Petrophytum elatius (S. Wats.) Heller, Cat. N. Am. Pl. 
ed. 2. 5. 1900. 
Spiraea caespitosa elatior S. Wats. Bot. King’s Expl.:81. 1871. 
Luetkea caespitosa elatior Britton, Trans. N. Y. Acad. Sci. 14: 31. 1894. 
A cespitose undershrub, but not so tufted as the preceding ; shoots of the season often 
2-3 cm. long, erect; leaves silky, oblanceolate, acute, 1.5-2 cm. long, 34 mm. wide, 
usually with more distinct petioles; peduncles 1-2 dm. high, silky, their leaves linear- 
oblanceolate, often 1-1.5 cm. long; inflorescence often branched, 4-10 cm. long; pedicels 
2-4 mm. long; hypanthium somewhat turbinate, 1 mm. deep; sepals lanceolate, 2 mm. 
long, acute or acuminate; petals oblanceolate, 2-3 mm. long. 
TYPE LOCALITY: Eastern end of Raft River Mountains, Utah. 
DISTRIBUTION : Mountains of Utah and Arizona. 
4, KELSEYA (S. Wats.) Rydb. Mem. N. Y. Bot. 
Gard. 1: 207. 1900. 
Eriogynia § Kelseya S. Wats. Proc. Am. Acad. 25: 130. 1890. 
Densely cespitose, pulvinate undershrubs, with short branches. Leavesentire, crowded, 
leathery, persistent. Flowers perfect, solitary, almost sessile, enclosed in the rosettes of 
the leaves. Hypanthium hemispheric. Sepals 5, valvate. Petals 5, imbricate. Stamens 
about 10; filaments filiform, about twice as long as the sepals; anthers didymous. Disk 
inconspicuous, entire. Pistils about 5; styles terminal; stigmas minute ; ovules 3-4, pen- 
dulous. Follicles leathery, not inflated, opening along both sutures; seeds elongate- 
fusiform. 
Type species, Eriogynia uniflora S. Wats. 
1. Kelseya uniflora (S. Wats.) Rydb. Mem. N. Y. Bot. Gard. 
1: 207. 1900. 
Eriogynia uniflora S. Wats. Proc. Am. Acad 25: 130. 1890. 
Luetkea uniflora Kuntze, Rev. Gen. 217, 1891. 
Spiraea untflora Piper, Erythea 7: 172. 1899. 
An undershrub, forming mats on the rocks; leaves crowded, 2-3 mm. long, more or less 
silky-pubescent; sepals oblong, obtuse, 1.5 mm. long; petals narrowly spatulate, nearly 3 
mm. long, white; stamens and pistils of about the same length ; follicles 2-2.5 mm. long, 
splitting first on the inner, later also on the outer sutures ; seeds usually 2. 
TYPE LOCALITY: The Gate of the Mountains, near Townsend, Montana. 
DISTRIBUTION : On cliffs in the mountains of Montana and northern Wyoming. 
ILLUSTRATION: Bot. Gaz. 15: pl. 14, 
5. LUETKEA Bong. Mém. Acad. St. Petersb. VI. 2: 130. Au 1832. 
Evriogynia Hook. Fl. Bor. Am, 1: 255. 1832. 
Cespitose undershrubs, with decumbent or creeping, stoloniferous branches. Leaves 
twice or thrice ternately dissected, grooved above. Flowers perfect, racemose. Hypan- 
thium hemispheric. Sepals 5, valvate. Petals 5, while in bud contorted. Stamens about 
20; filaments subulate, connate at the base; anthers didymous. Disk thickened, about 10- 
lobed. Pistils 4-6, usually 5, distinct; styles terminal, deciduous; stigmas truncate ; 
ovules several, pendulous. Follicles coriaceous, dehiscent on both sutures. Seeds linear- 
lanceolate, acute at both ends; embryo linear, radicle superior ; endosperm none. 
Type species, Luetkea sibbaldioides Bong. 
