ROSACES. (ROSE FAMILY.) 77 



3. P. Pennsylvanica, L. (WILD RED CHERRY.) Tree 20 to 30 feet 

 high, with light red-brown bark : leaves oblong-lanceolate, pointed, finely and 

 sharply serrate, shining, green and smooth both sides: fruit globose, light red, 

 very small, with thin and sour flesh ; stone globular. From Colorado north- 

 ward, and eastward to Newfoundland and Virginia. 



4. P. emarginata, Walpers, var. mollis, Brewer. Becoming a small 

 tree 25 feet high, with bark like that of an ordinary Cherry-tree, more or less 

 woolly-pubescent : leaves oblong-ovate to lanceolate, mostlij obtuse, crenately serru- 

 late, narrowed to a short petiole, with usually one or more glands near the 

 base of the blade, more or less woolly-pubescent on the under side: fruit globose, 

 black, bitter and astringent ; stone with a thick grooved ridge upon one side. 

 Bot. Calif, i. 167. Bitter Root Mountains and westward into Oregon and 

 California. 



* # Flowers in racemes terminating leafy branches, hence appearing after the 

 leaves, late in spring. 



5 P. demissa, Walpers. (WILD CHERRY.) An erect slender shrub 

 2 to 12 feet high : leaves ovate or oblong-ovate, abruptly acuminate, mostly 

 rounded or somewhat cordate at base, sharply serrate, usually more or less pubes- 

 cent beneath, with 1 or 2 glands at base : fruit purplish-black, or red, sweet and 

 edible, but somewhat astringent ; stone globose. From the Rocky Mountains 

 westward to the coast. 



6. P. Virginiana, L. (CHOKE CHERRY.) Leaves rarely at all pubes- 

 cent, more frequently somewhat cuneate at base: fruit dark red, very astringent 

 and scarcely edible ; the stone more ovoid and acutish : otherwise like the last, 

 but more diffuse in habit, and preferring stream banks and moist localities. 

 This species appears to be distributed throughout the whole of North Amer- 

 ica except in the region west of the Rocky Mountains. 



2. S PI 11-33 A, L. MEADOW-SWEET. 



Petals 5, rounded, nearly sessile. Stamens numerous. Carpels usually 

 5 or more. Perennial herbs or mostly shrubs : flowers white or rose-colored, 

 in compound corymbs or spikes. We follow the arrangement of Dr. Maxi- 

 mowicz in recognizing the four following genera as distinct from Spiraea. 

 Bot. Calif, ii. 443. 



* Erect shrubs : petals rose-colored or purplish : flowers in compound corymbs. 



1. S. betulifolia, Pallas. Glabrous or finely pubescent, with reddish 

 bark : leaves broadly ovate to ovate-oblong, acutely and unequally serrate or 

 incised, on short petioles or nearly sessile : flowers pale purple, the fastigiate 

 corymbs often leafy-bracted : ovules 5 to 8. S. cori/mbosa, Raf. Head- 

 waters of the Missouri, eastward in the Alleghany Mountains, westward to 

 N. California, and northward to Alaska. 



Var. rosea, Gray. Corolla rose-red. Proc. Am. Acad. viii. 381. W. 

 Wyoming, Idaho, and westward to Oregon and California. 



* # Low herbaceous perennials, woody at base : petals white : flowers in dense 



cylindrical spikes on scape-like stems. 



2. S. C8espitosa, Nutt. Cespitose, on rocks : leaves rosulate on the short 

 tufted branches of the woody spreading rootstock, oblanceolate or linear- 



