DICOTYLEDONS. 109 



A. Stone oval, compressed, leaves convolute in the bud, 

 branches often spiny. (Plums.) 



1. P. Americana Marsh. Wild Plum. 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, pubescent beneath ; petioles glandular ; flowers in 

 lateral, sessile umbels, appearing with or before the leaves ; pedicels 

 ^-| in. long; flowers |^-f in. in diameter; calyx pubescent within; 

 drupe globose, red or yellow, ^-1 in. in diameter. March- April. 

 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 ; drupe yellowish-red, subglobose, skin thin, 

 stone only slightly compressed. ]March-»Tune. In old fields. 



B. Stone globose or slightly compressed, leaves folded in 

 the bud, branches not spiny. (Cherries.) 



3. P. SEROTiNA Ehrh. Wild Black Cherry. Often becom- 

 ing a large tree 5 bark on old trees rough, nearly black ; leaves 

 rather thick, oval to lanceolate-ovate, acute or acuiuinate at the apex, 

 finely serrate with calloused teeth, glabrous above, pubescent on the 

 veins beneath; racemes terminal, long and spreading; flowers white; 

 drupes globose, about i in. in diameter, purplish-black. April-IVIay. 

 In rich woods. 



4. P. Caroliniana Ait. Cherry Laurel. A small tree ; 

 leaves evergreen, coriaceous, smooth and shiny, ovate or ovate- 

 lanceolate, acute, nearly entire ; racemes axillary, shorter than the 

 leaves; flowers white; drupe small, black, ovoid, not edible, soon 

 becoming dry. February-^Iarch. On river banks, and olten culti- 

 vated for ornament. 



5. P. Cerasus L. Cherry. Often becoming a large tree; 

 leaves oval or ovate, acute or acuminate at the apex, rounded at the 

 liase, irregularly serrate-dentate, smooth on both sides, resinous 

 wiuMi young; flowers in lateral umbels, white; pedicels long and 

 slender ; drupe globose, red or black. March-April. This is the 

 European si)ecies from which most of our cultivated varieties have 

 been developed. 



II. AMYGDALUS. 



Small trees; leaves sim})le, lanceolate, serrate, short- 

 jx'tioled; flowers solitary or clustered, like tliose of J'rtnius ; 



