AMYGDALACEAE 391 



i. Padus Mill. 



Leaves obovate or oval, sepals deciduous. 1. P. nana. 



Leaves ovate-lanceolate or oval, sepals persistent. 2. P. virginiana. 



1. P. nana (Du Roi) Roem. (Padus virginiana Roem.). Along 



river banks and in rocky situations: Newf. to Man., Br. Col., 



Ga., Neb., Tex. and Colo. 



Conn. Rare near the coast, increasing northward. 



N. Y. Occasional on L. I.; very rare and local on S. I., un- 

 known in the Bronx, rare in Westchester Co., thence increasing 

 and becoming very common northward. 



N. J. Somerset, Hunterdon and Hudson counties, increasing 

 northward. 



Pa. Throughout the area. 



Tertian', o: Cretaceous, rare or wanting, perhaps in Bucks Co., 



Pa. : Older Formations, increasing northward. 117-220 days. Sea 



level-4,020 ft. 



2. P. virginiana Mill. (Primus serotina Ehrh.). In woods and 



open places, S. Ont. to Fla., Dak., Kan. and Tex. 



Common throughout the range, except in the pine-barrens, there 

 rare or wanting. 



2. Primus [Tourn.] L. 



Plums; fruit usually with a ventral groove and a flattened 

 stone. 

 Drupe purple, with a bloom, less than 15 mm. thick. 



Leaves glabrous when mature, ovate; tree. I. P. alleghaniensis. 



Leaves pubescent on the lower surface, when 

 mature; shrubs. 

 Stone pointed at both ends; leaves acute. 2. P. maritima. 



Stone pointed at base; leaves obtuse. 3. P. Gravesii. 



Drupe red or orange, without a bloom, mostly more than 

 20 mm. thick. 

 Calyx lobes neither ciliate nor glandular. 4. P. americana. 



Calyx lobes ciliate and often glandular. 5. P. angustifolia. 



Cherries; fruit without a ventral groove; stone globose or 

 subglobose. 

 Shrubs; flowers 6-12 mm. broad. 



Leaves oblanceolate or spatulate. 6. P. pumila. 



Leaves oval, or oblong. 7. P. citneata. 



Trees; flowers 15-30 mm. broad, slightly less in No. 12. 

 Flowers appearing with or before the leaves. 



Introduced European trees; flowers not corym- 

 bose. 



