180 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



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

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



subherbaceouB, 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. angustifolia. 



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



8. P. cuneata. 



1. Prunus serotiua Ehrh. Wild black cherry. 

 Rich woods; frequent. Ma\\ Eastern U. S. (f'adus virginiana of Britt. &. Brown, 



Illustr. PI.) 



2. Prunus virginiana L. Choke cheeky. 

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



virginiana Mill.) 



3. Prunus americana Marsh. 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, alone; fence rows. Apr. Native of the Old 



World. 



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. ckicasa Michx.) 



8. Prunus cuneata Raf. 



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



82. CAESAIPINIACEAE. Senna Family. 



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



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

 Plants trees, armed with 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. Cercis canadensis L. Reduud. 



Woods; common. Apr. Eastern U. S. 

 Known also as Judas tree. 



2. GLEDITSIA I,. 

 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 ■ i.e. marilandica. 



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

 ceolate , 2. C. medsgeri. 



