116 FOUlirDATIONS OF BOTANY 



6. R. rubiginosa, L. Swebtbrier. 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.* 



Xin. PRTTHUS, Toum. 



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 6-lobed spreading limb, falling off after 

 flowering. Petals 6. 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. Slone oval, compressed ; fruit smooth when ripe. Branches often 

 spiny. (Plums.) 



1. P. americana, Marsh. Wild Plum. A smaU 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 

 ^-| in. long, flowers ^-| in. in diameter. Calyx downy within ; 

 fruit globose, red or yellow, ^-1 in. in diameter. Common in 

 woods.* 



2. P. angustifolia, Michx. Chickasaw Plum. 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 yeUowish-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. Peach. 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.') 



