PRUNUS 127 



tulose; buds round-ovoid, spreading. Introduced from Eurasia, 

 spread from cultivation and naturalized (Fig. 165). 



11. P. serotina Ehrh. Wild Black Cherry . A tree 20-35 m. 

 tall, the trunk 10-15 dm. in diameter; bark on old trees very 

 rough and black, on the branches smoother and gray-brown; inner 

 bark strongly and unpleasantly scented; twigs reddish-brown, buds 

 about 4 mm. long. Woods and open fields, Florida to Texas and 

 Mexico, north to New Brunswick, Minnesota and North Dakota 

 (Fig. 166). 



12. P^ virginiana L. Choke Cherry . A tall shrub or small 

 tree, 15 m. high, with grayish bark, the inner layers with a 

 rank disagreeable odor; twigs glabrous. Thickets, Newfoundland 

 to Saskatchewan, south to North Carolina, Missouri and Kansas 

 (Fig. 167). 



GYMNOCLADUS Lam. (Leguminosae) 



Large, deciduous, rough-barked tree. Twigs thick, terete 

 or 3-sided; pith large, round, continuous, salmon-colored. Buds 

 superposed, in raised silky pits; end-bud lacking. Leaf-scars 

 alternate, large, heart-shaped; bundle-traces 3 or 5, rather indef- 

 inite and divided; stipule-scars minute or lacking. 



1. _G. dioica (L. ) K. Koch. Kentucky Coffeetree . A tree 35 m. 

 tall, or less; bark varying from gray to dark brown, characterized 

 by sharp horny ridges; twigs very thick, finely pubescent, often . 

 coated with a crusty film, marked with fine lenticels; buds small, 

 downy, deeply sunken, surrounded by an incurved hairy ring of 

 bark; pods 1-2 dm. long, 3-4 cm. broad, often persisting until 

 late winter. Rich woods. New York to South Dakota, south to 

 Tennessee and Missouri; cultivated and naturalized eastwards and 

 northwards" (Fig. 168). 



GLEDITSIA L. (Leguminosae) 



Spreading deciduous trees usually armed with large branched 

 spines arising above the axils and persisting on the trunk. Twigs 

 zigzag, roundish; pith rounded, continuous, pale or light pink. 

 Buds glabrous, sessile, superposed, more or less covered by the 

 torn margin of the leaf-scar; end-bud lacking. Leaf-scars alter- 

 nate, relatively large, shield -shaped; bundle-traces 3; stipule- 

 scars none. Fruit a large legume (to 4 dm. long). 



1. G. triacanthos L. Honey- Locust . A tree with a maximum 

 height of 50 m. , usually much smaller; bark on young trunks smooth 



