240 ROSACEAE (ROSE FAMILY) 



Stamens inserted near base of calyx, near to the re- 

 ceptacle 23. Potentilla. 



Receptacle somewhat enlarged-spongy . . . . 24. Comarum. 

 Leaves compound; style persistent on the achene. 



Style jointed; the upper part deciduous . . . .25. Geum. 



Style not jointed 26. Sieversia. 



Fruit inclosed in the persistent receptacle, i. e., the calyx is con- 

 stricted over the fruit. 

 Herbaceous; receptacle dry. 



Calyx with hooked prickles . . . . . . 27. Agrimonia. 



Calyx not prickly 28. Sanguisorba. 



Shrubby; receptacle fleshy . . . . . . . . 29. Rosa. 



1. CERCOCARPUS H.B.K. MOUNTAIN MAHOGANY 



Shrubs or small trees, with simple evergreen leaves. Flowers small, axil- 

 lary, solitary. Calyx without bractlets; its tube long, cylindrical. Corolla 

 wanting. Stamens 15-25, in 2 or 3 rows on the deciduous limb of the calyx. 

 Fruit coriaceous, linear, terete, villous, included in the enlarged calyx-tube 

 and tailed with the elongated and plumose style. 



Leaves not resinous, obovate . . 1. C. parvifolius. 



Leaves resinous, narrow. 



Oblong-lanceolate, 4-6 cm. long . . . . . . . 2. C. ledifolius. 



Linear, 2-4 cm. long 3. C. intricatus. 



1. Cercocarpus parvifolius Nutt. H. & A. Bot. Beechey Voy. 337. 1841. 

 A shrub 6-30 dm. high (sometimes twice as high): leaves cuneate-obovate, 

 coriaceous, serrate towards the obtuse or rounded summit, more or less silky 

 above, densely hoary-tomentose beneath: flowers on short slender pedicels: 

 limb of calyx with short teeth: tail of achene often 10 cm. long. Bleak stony 

 slopes; from the plains east of the Rocky Mountains to the Pacific. 



2. Cercocarpus ledifolius Nutt. T. & G. Fl. N. A. 1: 427. 1840. A shrub 

 or small tree, 1-3 m. high: leaves entire, oblong-lanceolate, 4-6 cm. long, 

 thick-coriaceous, margins more or less revolute, nearly glabrous and some- 

 what resinous above, densely tomentose beneath: flowers sessile, tomentose, 

 solitary or 2-3 in the axils: calyx deeply toothed: tail of the achene at length 

 4-7 cm. long. Utah, western Wyoming, and west to California. 



3. Cercocarpus intricatus Wats. Proc. Am. Acad. 10: 346. 1875. A low 

 shrub, rarely more than 1 m. high, intricately branched: leaves linear, closely 

 revolute, about 3 cm. long; otherwise as in the preceding except that the 

 flowers and fruits are much smaller. From northeastern Wyoming and 

 Montana to Utah and Nevada. 



2. COWANIA Don. CLIFF ROSE 



Shrubs, with small coriaceous entire or deeply toothed gland-dotted leaves. 

 Flowers showy, terminal, short-peduncled. Calyx-tube turbinate. Petals 5, 

 obovate. Stamens numerous, in 2 rows inserted with the petals at the throat 

 of the calyx-tube. Carpels about 5, densely villous. Fruit coriaceous, narrowly 

 oblong, striate, partly included in the enlarged calyx-tube, and tailed with 

 the elongated plumose styles. 



1. Cowania mexicana Don. in Trans. Linn. Soc. 14: 575. 1825. A much 

 branched shrub, 3-12 dm. high; the trunk with abundant shreddy light- 

 colored bark: leaves approximate upon the short branchlets, cuneate-obovate 

 in outline, pinnately 3-7-lobed, dark green above, tomentose beneath: flowers 

 yellow, the calyx-tube attenuate into a short glandular-hairy pedicel: tail 

 of the achene at length 5 cm. long or more. Northern Utah and southern 

 Colorado to central Mexico. 



/ 



3. PURSHIA DC. 



A low intricately-branched prostrate shrub, or in the far west taller and 

 erect, with fascicled cuneate leaves, and flowers terminal on the short branch- 



