124 KEY AND FLORA 



3. R. Woodsii Lindl. Stems 3-36 in. high, with slender spines which 

 are often wanting above. Stipules rather broad, entire ; leaflets usu- 

 ally 5-7, varying from obovate to lanceolate, rather obtuse at the apex, 

 narrowed at the base, somewhat serrate. Flowers corymbed or solitary. 

 Sepals erect on the globose or somewhat ovoid fruit. Prairies W. 



4. R. rubiginosa L. Sweetbrier. Stem erect or curving, armed 

 with stout recurved prickles. Leaves with 5-7 leaflets, the latter 

 broadly oval, coarsely serrate, glandular-bristly beneath, aromatic. 

 Flowers white or pink. Sepals widely spreading, deciduous. Fruit 

 obovate, slightly bristly. Common in cultivation and sometimes wild.* 



5. R. Carolina L. Swamp Rose. Stems 4-8 ft. high, with stout 

 and generally recurved prickles. .Stipules long and narrow ; leaflets 

 commonly downy beneath, finely serrate. Flowers several in a corymb, 

 bright rose color. Sepals spreading and falling off after flowering. 

 Damp woods and borders of swamps. 



6. R. virginiana Mill. Dwarf Wild Rose. Stems varying in 

 height from less than a foot to 6 ft., with stout, somewhat hooked 

 prickles. Stipules rather broad; leaflets small, thickish and glossy 

 above, coarsely toothed toward the tip. Flowers corymbed or soli- 

 tary, pale rose color. Sepals spreading and falling oH after flowering. 

 Moist ground and swamps. 



7. R. humilis Marsh. Pasture Rose. Stem erect, branched, 

 usually armed with stout stipular prickles and with bristles, but 

 sometimes nearly smooth, 1-3 ft. tall. Leaves mostly of 5 leaflets; 

 stipules entire ; leaflets oblong-lanceolate or oval, shining above, 

 pale beneath, sharply serrate. Flowers solitary or 2-3 together, 

 2-3 in. broad, pink. Peduncles and calyx glandular-downy. Sfipals 

 leaf-like, spreading, finally deciduous. Styles distinct. Fruit globose, 

 bristly-hairy. On dry soil; our most common wild rose. S.* 



XIV. PRUNUS L. 



Trees or shrubs. Leaves simple, with stipules^ which are 

 often small or fall off early. Calyx with a bell-shaped or urn- 

 shaped, tube and 5-lobed spreading limb, falling off after flower- 

 ing. Petals 5 ; stamens 3-5 times as numerous, or indefinite, 

 inserted on the throat of the calyx tube. Pistil 1, long-styled, 

 with 2 ovules, ripening into a single drupe. 



B. Fl. species 8 (Ami/f/dalus). 



A. Stone more or less spherical ; fruit smooth when ripe. Branches 

 not spiny. (^Cherries.') 



1. P. serotina Ehrh. Wild Black Cherry. Often becoming a 

 large tree ; bark on old trees rough, nearly black. Leaves rather 



