180 COJJTRIBUTIONS FEOM THE NATIONAL HERBARIUM. 



Leaves glabrous; inner scales of flower bud appressed; fruit sour. .4. P. cerasus. 

 Leaves pubescent beneath, at least on the veins; inner scales of flower bud 



subherbaceous, spreading; fruit sweet 5. P. avium. 



Flowers small, the petals 4-6 mm. long. 



Leaves orbicular-ovate 6. P. mahaleb. 



Leaves elliptic to oblong. 



Leaves elliptic, serrulate to the base, not paler beneath 7. P. angustifolla. 



Leaves spatulate-oblong, not serrulate along the cuneate base, pale beneath. 



8. P. cxmeata. 



1. Prunus serotina Ehrh. Wild black cherry. 

 Rich woods; frequent. Mav. Eastern U. S. (Padus virginiana of Britt. & Brown, 



lUustr. Fl.) 



2. Prunus virginiana L. Choke cherry. 

 Thickets and river banks; rare. May. Northern states, south to Ga. (Padus 



virginiana Mill.) 



3. Prunus americana Mai'sh. Wild plum. 

 Thickets and fence rows; frequent. Apr. Southern states, north to Conn. 



4. Prunus cerasus L. Sour cherry. 

 Occasionally escaped from cultivation. Apr. Native of the Old World. 



5. Prunus avium L. Sweet cherry. 

 Occasionally escaped from cultivation, along fence rows. Apr. Native of the Old 



World. 



m 



6. Prunus mahaleb L. Mahaleb. 

 Roadsides and thickets; infrequent. May. Originally from Eur. 



7. Prunus angustifolia Marsh. Chickasaw plum. 

 Thickets; frequent. Apr. Southern states, north to Del. (P. chicasa Michx.) 



8. Prunus cuneata Raf. 



Thickets in saijdy soil; infrequent. May. Northern states, south to N. C. 



82. CAESAIPINIACEAE. Senna Family. 



Leaves simple, entire; flowers reddish purple; pods winged. Trees 1. CEKCIS. 



Leaves compound, of numerous leaflets; flowers yellow or green; pods not winged. 

 Plants trees, armed Avitli spines; flowers small, inconspicuous, greenish. 



2. GLEDITSIA. 

 Plants herbaceous, unarmed; flowers mostly large, showy, bright yellow. 



Plants perennial, glabrous or nearly so; leaflets large, mostly 3.5-5 cm. long; pods 



. jointed 3. CASSIA. 



Plants annual; leaflets small, mostly less than 2 cm. long; pods not jointed. 



4. CHAMAECRISTA. 

 1. CERCIS L. 

 1. Cerois canadensis L. Reduud. 



Woods; common. Apr. Eastern L'. S. 

 Known also as Judas tree. 



2. GLEDITSIA L. 

 1. Gleditsia triacanthos L. Honey locust. 



Woods; common. May. Eastern states, south to Ga. 



Often planted as a shade tree; remarkable for the large branched thorns usually 

 found along the trunk; pods broad and flat, often 30-45 cm. long. 



3. CASSIA L. Wild senna. 



Joints of the pod as long as broad or longer; gland on the petiole usually club-shaped; 

 stipules very narrowly linear 1. C. marilandica. 



Joints of the pod broader than long; glands conic or cylindric; stipules linear-lan- 

 ceolate 2. C. medsgeri. 



