187 



TREE OF HEAVEN. 



Ailanthus glandulosa, Desfontaines. 



FAMILY AND GENUS DESCRIPTION The Quassia family, Simarubaceae, comprises about 

 30 genera with 150 species found mostly in the tropics and the warmer parts of both the east- 

 ern and western hemispheres. Three genera, each with 1 tree species, are native to the south- 

 ern part of the United States. A single species of a fourth genus has been introduced from 

 China. This genus, Ailanthus, contains 7 species all native to eastern Asia. No member of this 

 family is native to Pennsylvania. 



FORM May reach a height of 100 ft. with a diameter of 3 ft., but usually much smaller. 

 Trunk usually short, but sometimes long, bearing stout branches with few branchlets. Crown 

 wide, high, and flat-topped. 



BARK On younger trunks smooth, thin, light gray, somewhat roughened with fissures. Ridges 

 usually dark and stand in strong contrast with the light fissures. On old trunks thin, close, 

 roughened with diamond-shaped fissures, dark gray and sometimes black. See Fig. 99. 



TWIGS Stout, clumsy, yellowish-green to reddish-brown, covered with a fine velvety down 

 and numerous, longitudinally-elongated, ochre-colored, scattered lenticels. Pith large, rather 

 hard, light brown. When broken or crushed the twigs give forth a rank smell. Longitudinal 

 striations may appear after outer covering of twigs scales off. 



BUDS Alternate; terminal bud absent; false terminal bud often present; reddish-brown, 

 downy, about 1/8-1/6 of an inch long, located In notch of upper surface of the leaf-scar, 

 covered with scales; the two outer scales do not quite cover the bud, hence they leave a 

 narrow slit running parallel with the twig. 



LEAVES Alternate, compound, li-3 ft. long, composed of 11-41 leaflets. Leaflets ovate- 

 lanceolate, 3-5 inches long, acuminate at apex, truncate to heart-shaped at base, almost entire 

 with a few coarse teeth towards the base of the -leaf. Glands may be present on the lower side 

 of the leaflets near or on the small basal lobes. 



LEAF-SCARS Alternate, large, conspicuous, more than 2-ranked, heart-shaped, lighter In 

 color than twig, have raised margins and contain about 8-14 conspicuous buridle-scars arranged in 

 a V-shaped line. Bundle-scars sometimes curved or compounded. 



FLOWERS Appear about June when leaves are fully developed. Stamina te and pistillate 

 flowers occur on separate trees. Individual flowers small, green, and arranged In terminal 

 panicles. The staminate have a very unpleasant odor. 



FRUIT Borne only on female or pistlilate trees in conspicuous clusters which often persist 

 far into winter. Each fruit consists of a spirally twisted wing about 1J inches long and 5 

 of an inch wide, in the center of which a small seed is located. 



WOOD Ring-porous; with conspicuous rays; white to pale yellow, light, soft, weak, and open- 

 grained. Used in cabinet work, for wooden ware, and for charcoal. 



DISTINGUISHING CHARACTERISTICS The Tree of Heaven, also known as Paradise Tree, 

 Ailanthus, Haven-Wood and Chinese Sumach, can be distinguished in winter by its stout 

 twigs which are coversd with fine down and conspicuous scattered lenticels, and contain a large 

 light brown pith; twigs are roughened by large heart-shaped leaf-scars containing a curved line 

 of bundle-scars. The small gaping downy buds situate in the notch on the upper surface of the 

 leaf-scars, are also characteristic. In summer the large alternate leaves with 11-41 leaflets which 

 often have glands on the lower surface, are distinctive. The bark cannot be confused with that 

 of any native tree. 



RANGE Native of China. Widely planted In Ontario, Canada and the northeastern United 

 States. Frequently it has escaped cultivation and is found in abandoned fields, in forest borders, 

 and along fences. 



DISTRIBUTION IN PENNSYLVANIA Naturalized extensively in the eastern, southern, cen- 

 tral and western parts of the State. Escaped cultivation in many places. Thickets of it are 

 found in Franklin county. In some places it is not only found in the open fields and along 

 fences but is migrating into the forest with the hardwoods and pines. 



HABITAT Tolerates almost any kind of soil and dense shade. Its rapid growth often 

 enables it to dominate over its associates. 



IMPORTANCE OF THE SPECIES This tree is of no special importance as a forest tree and 

 has serious demerits as a shade or park tree. It was introduced into England about 1751 by 

 missionaries and from there it was soon brought to America and first planted near Philadelphia. 

 At first it was a very popular tree, but it soon lost favor. The staminate flowers are very 111 

 smelling. The wood is inferior in quality. The rapid and free growth of the root sprouts 

 makes it almost impossible to eradicate it when once established. Its aggressive migration 

 Into fields and forest is undesirable. 



