ROSACEAE. 201 



stamens numerous; styles 2-5; pome fleshy or berry-like, the 

 2-5 carpels or cells of a papery or cartilaginous texture, 2-seeded, 



Leaves simple; cyme simple. P. diver sifolia. 

 Leaves pinnate; cyme compound. 



Leaflets acute, serrate the whole length. P. sitchensis. 



Leaflets obtuse, serrate only at the apex. P. occidentalis. 



Pyrus diversifolia Bong. Wild Crab-apple. Small tree, 5-10 m. high, 

 somewhat spiny; leaves ovate-lanceolate, acute r E acuminate, sometimes 

 3-lobed, serrate, pubescent beneath; flowers white, 'in a simple cyme; fruit 

 oblong, green or purplish, depressed at each end. 



In swamps, common. 



Pyrus sitchensis (Roem.) Piper. Mountain Ash. Shrub, 2-5 m. high, with 

 smooth bark; young branches pubescent; leaves pinnate, 12-20 cm. long; 

 leaflets 4-6 pairs, mostly oblong, acute or acuminate, simply or doubly serrate, 

 glabrous or nearly so, shiny above, 2-6 cm. long, 1-2 cm. broad; cymes dense, 

 compound, 8-12 cm. broad; flowers white, 8 mm. broad; calyx and pedicels 

 loosely woolly-pubescent; fruit bright-red, about 6 mm. in diameter. 



In the mountains at low altitudes. 



Pyrus occidentalis Wats. Low shrub, about 1 m. high; leaflets 7-11, 

 oblong, obtuse, serrate near the tip, dull above, paler beneath; cymes rather 

 small; fruit purplish with a bloom. 



In the mountains, at about the limit of trees. 



267. OPULASTER. NINEBARK. 



Branching shrubs; leaves petioled, simple, palmately-lobed; 

 flowers in umbel-like corymbs; calyx 5-lobed; petals 5, round, 

 on the calyx-tube; stamens many, distinct, on the calyx-tube; 

 pistils 1-5, more or less united; follicles 1-5, 2-valved; seeds 

 2-4; endosperm copious. 



Opulaster opulifolius (L.) Kuntze. Shrub, 2-5 m. high, the branches 

 spreading and covered with a thin flaky brownish bark; leaves broadly ovate 

 to orbicular, cordate, palmately 3-5-lobed, somewhat doubly dentate, nearly 

 glabrous above, stellate pubescent beneath, 2-8 cm. long; petioles 1-2 cm. 

 long; inflorescence a dense corymb; petals white, obovate, longer than the 

 blunt calyx-lobes; carpels membranaceous, glabrous, a half longer than the 

 calyx. 



On stream banks. The western form is by some authors considered distinct 

 under the name O. capitatus (Pursh) Kuntze. 



268. LUTKEA. 



Low cespitose shrubs with decumbent stoloniferous branches; 

 leaves 2-3 times ternately dissected; flowers perfect, in racemes; 

 disk thickened, 10-lobed; calyx-tube hemispheric; sepals 5; 

 petals 5; stamens numerous; pistils usually 5, distinct; styles 

 terminal, deciduous; stigmas truncate; ovules several; follicles 

 coriaceous; seeds linear-lanceolate. 



Lutkea pectinata (Pursh) Kuntze. Densely matted; stems creeping, 

 slender, woody; leaves twice or thrice cleft into narrow acute spreading lobes, 

 glabrous; flowering stems 5-10 cm. high; racemes 2-3 cm. long. 



In alpine meadows, abundant, often forming extensive mats. 



