116 * FOUNDATIONS OF BOTANY 
5. 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 cultiva- 
tion and sometimes wild.* 
XII. PRUNUS, Tourn. 
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 
flowering. 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 stone-fruit. 
A. Stone oval, compressed ; fruit smooth when ripe. Branches often 
spiny. (Plums. ) 
1. P. americana, Marshh Witp Pium. A _ small tree, bark 
thick and rough, branches spiny. Leaves ovate or obovate, acumi- 
nate at the apex, rounded or cordate at the base, sharply serrate, 
rather thick, downy beneath; petioles glandular. Flowers in lat- 
eral, sessile umbels, appearing with or before the leaves; pedicels 
4-3 in. long, flowers $—-3 in. in diameter. Calyx downy within; 
fruit globose, red or yellow, 3-1 in. in diameter. Common in 
woods.* 
2. P. angustifolia, Michx. CurckaAsAw Pium. A small tree 
with spiny branches. Leaves lanceolate or oblong-lanceolate, acute — 
at the apex, usually obtuse at the base, finely and sharply serrate, 
rather thin, smooth. Flowers in lateral, sessile umbels, pedicels 
short. Calyx smooth. Fruit yellowish-red, subglobose, skin thin, 
stone only slightly compressed. In old fields, S.* ; 
B. Stone deeply furrowed and pitted; fruit downy when ripe. 
Branches not spiny. (Peaches and almonds.) 
3. P. persica, Sieb. and Zucc. Pracu. A tree with a rounded 
top; bark nearly smooth. Leaves lanceolate, taper-pointed, finely 
serrate, smooth on both sides; petioles usually bearing 2 or 4 
crescent-shaped or cup-shaped glands. Flowers pink, scaly-bracted. 
Fruit ovoid, with a seam along one side. Often escaped from culti- 
vation.* 
C. Stone more or less spherical ; fruit smooth when ripe. Branches 
not spiny. (Cherries.) 
