170 



SlMARUBACEAE. 



Ailanthus. Tree of Heaven. 

 (Family Simarubaceae). 



Rather smooth-barked loosely 

 branched trees with peTsistently 

 prominent lenticels: deciduous. 

 Twigs coarse, somewhat 3-sided: 

 pith large, homogeneous, round- 

 ish, becoming colored. Buds sol- 

 itary, sessile, hemispherical, rela- 

 tively small, with 2 or 4 exposed 

 scales, the end-bud fallen, leaving 

 a large scar. Leaf-scars alter- 

 nate, cordately elliptical-shield- 

 shaped, slightly raised, large: 

 bundle-traces about 9: stipule- 

 scars lacking. 



Winter-character references: 

 Ailanthus glandulosa. Blakeslee 

 & Jarvis, 334, 524, pi.; Bosemann, 

 61; Hitchcock (3), 9; Otis, 170; 

 Schneider, f. 35, 99; Shirasawa, 

 236; Ward, 1:118, f. 59. 

 Like Gymnocladus, Ailanthus 

 offers exceptionally good opportunities for recognizing that 

 year after year the branches of certain trees are continued 

 by development of axillary or lateral buds, the tip of each 

 year's growth disappearing early by a clean-cut abscission. 



Mr. Swingle, after reviewing the early European history 

 of Ailanthus, shows that the commonly cultivated species 

 should be called A. altissima, in the Journal of the Washing- 

 ton Academy of Sciences, of August 19, 1916. 



1. Twigs prickly. A. Vilmoriniana. 

 Unarmed. 2. 



2. Twigs puberulent. (1). A. glandulosa. 

 Twigs glabrescent. A. glandulosa pendulifolia. 



