RHAMNACEAE. l6l 



4 or 5, on the disk, or sometimes none; stamens 4 or 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 

 fleshy. 



Fruit a drupe; flowers solitary or in umbels. 226. Rhamnus, 161. 



Fruit a dry capsule; flowers in panicles. 227. Ceanothus, 161. 



226. RHAMNUS. 



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

 veined, with small deciduous stipules; flowers greenish, polygamous 

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

 bell-shaped, lined with the disk, both free from the ovary; petals 

 5, small, oblong, sessile, acute or none; stamens 4 or 5 ; ovary 2-4- 

 celled; fruit a berry-like drupe, with 2-4 separate seed-like 

 nutlets. 



Shrub; petals wanting; leaves nearly glabrous beneath. R. alnifolia. 



Tree; petals present; leaves downy beneath. R. purshiana. 



Rhamnus alnifolia L'Her. Shrub, 1-2 m. high; leaves oval, acute at each 

 end, serrate, 5-8 cm. long, straight veined; petioles slender, puberulent; 

 fruit black, 3-seeded. In swamps near Spokane and about Lake Coeur d'Alene, 

 Idaho. 



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

 dark-gray bark; young twigs pubescent; leaves elliptic, obtuse or acuminate, 

 rounded at base, somewhat undulate, denticulate, pubescent, especially be- 

 neath, 5-15 cm. long; petioles 1-2 cm. long, downy; umbels stout-peduncled, 

 8-15-fIowered; flowers 3-5 mm. long; sepals 5; petals minute, hood-shaped; 

 fruit black, obovoid, as large as a pea, 3-seeded, insipid. Along streams, un- 

 common. Bark used medicinally under the name Cascara sagrada. 



227. CEANOTHUS. 



Shrubs, sometimes evergreen; leaves alternate, petioled; 

 flowers perfect, in small umbel-like clusters, forming dense 

 panicles at the summits of naked branches; calyx 5-lobed; calyx 

 and disk adherent to the ovary; petals hooded, spreading; 

 stamens 5; ovary 3-lobed; fruit 3-lobed, dry and very oily, 

 splitting into its three carpels when ripe. 



Evergreen; leaves varnished. C. velutinus. 



Deciduous; leaves not varnished. C. sanguineus. 



Ceanothus velutinus Dougl. Sticky Laurel. Stout shrub, 1-2 m. high, 

 much branched; branchlets puberulent; leaves oval, obtuse, subcordate at 

 base, prominently 3-nerved, finely denticulate, thick and firm, glabrous and 

 gummy above, puberulent beneath, 5-8 cm. long; petioles stout; flowers white, 

 in terminal panicles 5-10 cm. long; peduncles stout, puberulent; pedicels 

 slender; carpels subglobose, 3-lobed above, nearly smooth. Thatuna Hills, 

 common. 



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