1 1 4 Flora of the Palouse Region 



styles 2; ovary 2-lobed, 2-celled; ovules 2 in each cell: fruit a 

 double samara, 2-winged above, separable at maturity, each 

 1 -seeded. 



A. glabrum var. douglasii Piper, n. comb. (A, dougiasii Hook.) Small 

 tree, 3-10 m. high, with smooth light-gray bark: leaves simple, rarely 

 3-foliolate, orbicular, acutish, 5-lobed, coarsely serrate, truncate or subcor- 

 date at base, glabrous, dark-green above, paler beneath, 5-10 cm. long; 

 petiole slender: flowers polygamous, in small corymbs: petals narrow, spat- 

 ulate-oblong, veiny, about as long as the similar sepals: fruit glabrous, 

 roughened, the wings diverging at less than a right angle, 2.5-3 cm - l° n g- 

 Thatuna Hills, along streams. Leaves larger and differently toothed from 

 the true A. glabrum of the Rocky Mountains. 



184. GEOSSOPETAEON. 



Low and rigid shrubs, with slender spinescent branches: leaves 

 small, alternate, sessile, entire; stipules minute, setaceous-subu- 

 late: flowers small, perfect, solitary, terminating short axillary 

 branches or spur-like fascicles: calyx deeply 4-5 -cleft: petals 4 or 

 5: stamens 8 or 10: style short or none; ovary i-celled, of a single 

 ovoid carpel; ovules 2: fruit a coriaceous follicle, 1-2-seeded. 



G. spinescens Gray. Low much branched shrubs, somewhat spiny, 1 in. 

 or less high: leaves numerous, oblanceolate, acute, short-petioled, glabrous 

 or puberulent, pale-green and glaucous, 6-16 mm. long; stipules minute, 

 usually reddish: flowers on pedicels as long as the leaves, petals yellow, 

 narrow, 6 mm. long: capsules ovoid, acutely beaked, striate, often curved. 

 In basalt crevices, opposite Lewiston. 



Family 46. RHAMNACEAE. 



Erect or climbing shrubs or small trees: leaves simple with small 

 stipules: flowers small and regular, sometimes polygamo-dioecious, 

 often apetalous: disk fleshy: calyx 4-5-toothed: petals 4-5, on the 

 calyx-tube, or none: stamens 4-5, perigynous, alternate with the 

 sepals and opposite the petals: ovary sessile: fruit a drupe or pod, 

 with 1 seed in each cell; endosperm sparingly flesh)'. 



Calyx and disk free from the ovary. 185. RHAMNTJS. 



Calyx and disk adherent to the base of the ovary. 186. ceanothus. 



185. RHAMNUS. 



Shrubs or small trees: leaves alternate, petioled, pinnately- 

 veined, with small deciduous stipules: flowers greenish, polygam- 

 ous or dioecious, in axillary clusters: calyx 4-5-cleft; calyx-tube 

 bell-shaped, lined with the disk; calyx and disk free from the 

 ovary: petals 5, oblong, sessile, acute: stamens 4-5; ovary 2-4- 

 celled: fruit a berry-like drupe, with 2-4 separate seed-like nutlets. 



R. purshiana DC. Small tree, 3-12 m. high, with nearly smooth dark- 

 gray bark: young twigs pubescent; haves elliptic, obtuse or acuminate, 



