ROSACEAE (ROSE FAMILY) 247 



lets. Calyx funnel-shaped. Petals exceeding the calyx-lobes, yellow. Sta- 

 mens about 25, in one row. Carpels 1, or sometimes 2, narrowly oblong. 

 Fruit pubescent, attenuate at each end, exserted. 



1. Purshia tridentata DC. Trans. Linn. Soc. 12: 158. 1817. Prostrate- 

 spreading, or an erect shrub 1-3 m. high, with brown or grayish bark; the 

 young branches and numerous short branchlets pubescent: leaves cuneate- 

 obovate, 3-lobed at the apex, petioled, white-tomentose beneath, greener 

 above: calyx tomentose with some glandular hairs: petals spatulate-obovate : 

 carpels oblong, densely pubescent, striate, attenuate at each end, 8-12 mm. 

 long, exserted. (Kunzia tridentala, in lit.) Throughout the Rocky Moun- 

 tains, and west to California and Oregon. 



I 

 4. COLEOGYNE Torr. 



A diffusely branched somewhat spinescent desert shrub, with coriaceous 

 leaves and flowers terminal on short branchlets. Flowers yellow, showy, 

 subtended by 1 or 2 pairs of 3-lobed bracelets. Calyx with a membranaceous 

 margin, colored within. Stamens numerous, inserted upon the base of a 

 tubular torus which includes the ovary. Style lateral, very villous at base, 

 twisted, exserted, persistent. Fruit glabrous, included. 



1. Coleogyne ramosissima Torr. PL Frem. 8. pi. 4. 1850. The short rigid 

 branches opposite and spinescent; bark gray: leaves approximate upon the 

 branchlets, linear-oblanceolate, puberulent with appressed hairs attached by 

 the middle: tube of the torus membranaceous, dilated below and narrowed 

 to the shortly 5-toothed apex, densely white-villous within: achene somewhat 

 compressed, the obtuse apex incurved. From southern Colorado to southern 

 California. 



5. HOLODISCUS Maxim. 



Unarmed shrubs with simple toothed or lobed exstipulate deciduous leaves, 

 and terminal panicles of numerous white flowers. Calyx deeply 5-cleft, nearly 

 rotate. Petals 5, rounded. Stamens 20, inserted on an annular perigynous 

 disk. Pistils 5, distinct, becoming 1-seeded hairy carpels, tardily dehiscent 

 by the dorsal suture, or indehiscent. 



1. Holodiscus dumosus (Nutt.) Heller, Cat. N. A. PL 4. 1898. Low shrub 

 with slender branches, 4-10 dm. high: leaves small, ovate, incisely toothed, 

 glabrate above, white-tomentose beneath, cuneate into a short margined 

 petiole: panicle branched, dense: calyx tomentose; the lobes acute, spreading: 

 carpels 5, compressed, hirsute. (H. microphyllus Rydb. Bull. Torr. Bot. 

 Club 31: 559. 1904.) Colorado, west to the Sierras. 



6. PHYSOCARPUS Maxim 



Shrubs with simple toothed or lobed alternate leaves, membranaceous de- 

 ciduous stipules, and rather large white flowers in simple terminal corymbs. 

 Calyx 5-cleft, persistent. Petals 5, rounded, sessile. Stamens numerous, 

 perigynous. Carpels 1-5, distinct, often stipitate, becoming membranaceous 

 inflated capsules; ovules few to several. Seeds with shining stony testa. 

 (Opulaster of Am. authors.) 



Carpels somewhat inflated. 



Leaves evidently pubescent . . . . .. . .1. P. pubescens. 



Leaves glabrous or glabrate. 



Pedicels conspicuously bracteate 2. P. Ramaleyi. 



Pedicels ebracteate. 



Mature carpels twice as long as the calyx, 2, united below . 3. P. intermedius. 

 Mature carpels not surpassing the calyx, 1 or 2, united nearly 



to the summit 4. P. monogynus. 



Carpels compressed laterally . . f . 5. P. malvaceus, 



