158 American Midland Naturalist Monograph No. 2 



5. Leaves ovate to suborbicular, apiculate, crenate, glandular between 

 the teeth; fruit ovoid, black or nearly so, 7-10 mm. long; road- 

 sides, occasionally escaped from cult.; introd. from Eur. May. 



Mahaleb Cherry P. mahaleb L. 



4. Dwarf shrubs; leaves oblanceolate, acute, serrate except toward the 

 cuneate base; fruit nearly globose, black, acid, 1-1.5 cm. in diameter 



at maturity; sandy soil, n. 111. Apr. -May. Sand Cherry 



P. pumila L. 



3. Flowers larger, the petals 7-16 mm. long. 



7. Leaves serrate, the sharp teeth not ending in a gland; petals 8-10 



mm. long; calyx-lobes not glandular-serrulate. 



8. Petioles glabrous beneath; lower surface of mature blades glabrous 



except along the veins; young twigs glabrous; borders of woods, 



common. May. Wild Plum P. atnericana Marsh. 



8. Petioles pubescent all around; blades usually more or less softly 



pubescent beneath; young twigs puberulent; woods, and road- 

 sides, common. Apr.-May. [P. americana var. mollis T. SC G.] 



P. lanata (Sudw.) Mack. & Bush 



7. Leaves crenate, the blunt teeth ending in a gland; calyx-lobes more 

 or less glandular-serrulate; petioles glabrous beneath; twigs gla- 

 brous. 



9. Calyx-lobes pubescent on both sides; petals 8-10 mm. long; leaves 



lanceolate; roadsides and edges of woods, common. Apr.-May. 



Hortulan Plum P. hortnlana Bailey 



9. Calyx-lobes glabrous within; petals 12-15 mm. long; leaves broadly 

 obovate or oval; river banks, woods, and roadsides thickets, n. 

 111. May. Canada Plum P. nigra Ait. 



2. Flowers several to many, in elongate racemes. 



10. Leaves thin, obovate, sharply serrate with erect or spreading teeth; 

 sepals nearly orbicular, glandular-serrate, deciduous; woods and 

 thickets, chiefly in the n. and centr. parts of the state. May. [P. 

 nana DuRoi} Common Chokecherry. The form with the lower sur- 

 face of the leaves, young twigs, and rachis of inflorescence pubes- 

 cent is f. deamti G. N. Jones P. virginiana L. 



10. Leaves firm, oval or lanceolate, crenulate-serrate with incurved teeth; 

 sepals obscurely glandular, persistent; woods, and along fences, 

 common throughout 111. May. [P. virginiana sensu Ehrh., non L.; 



Padus virgimana (L.) Mill.} Wild Black Cherry 



P. serotina Ehrh. 



84. Leguminosae Juss. — Pea Family 



1 . Trees or shrubs. 



2. Leaves simple, entire, suborbicular to reniform; flowers pink, jierfect, in sessile 

 umbels, appearing before tbe leaves; pods 6-8 cm. long, pointed at eacli end.... 

 3. Cercis 



2. Leaves compound. 



3. E.rect shrubs or trees. 



4. Shrubs: fjcx-ers in racemes. 



