30 The Trees of Great Britain and Ireland 



AILANTHUS GLANDULOSA, Ailanthus Tree 



Ailantkus glandulosa, Desfontaines, Mim. Acad. Paris. 1786(1789), 263, t. 8; Loudon, Arb. et 

 Frut. Brit. i. 490 (1838); Britten and Brown, Illustrated Flora of the Northern United States 

 and Canada, ii. 355, Fig. 2272 (1897). 



A tree attaining 100 feet in height and 13 feet in girth; branches massive 

 and forming an oval crown, which becomes flattened at the top in old trees. Bark 

 smooth, grey, or dark brown, and marked by longitudinal, narrow, pale-coloured 

 fissures, which are very characteristic. 



Leaves deciduous, compound, 1-3 feet long, imparipinnate, with 7-9 (sometimes 

 even 20) pairs of leaflets, which are either opposite or nearly so, shining above, pale 

 and glabrous (occasionally slightly pubescent) beneath, and unequally divided by the 

 midrib. Each leaflet is stalked, ovate, or ovate-lanceolate, acute or acuminate at 

 the apex, cordate or truncate at the base, entire in margin, except that near the base 

 there are 1-4 pairs of glandular teeth. Stipules absent. The leaves appear late 

 in spring, and exhale when rubbed a disagreeable odour which renders them 

 distasteful to animals. They fall off late in autumn, absciss layers being formed 

 at the base of the leaflets as well as of the main stalk ; the former usually drop first. 



Flowers appearing in July and August in large panicles at the summit of the 

 branchlets, either unisexual or hermaphrodite ; but as a rule the trees are practically 

 dioecious, and those bearing staminate flowers give off an objectionable odour. 



Fruit, 1-5 keys, resembling those of the ash, linear or oblong, membranous 

 veined, with a small indentation above the middle on one side, close to where the 

 seed is located ; and the wings on both sides of the seed are slightly twisted, so 

 that the fruit in sailing through the air moves like a screw. The keys are bright 

 red or purplish brown in colour, and are very conspicuous amidst the green foliage. 



Seedling : the cotyledons appear above the* soil on a caulicle about an inch 

 long and are foliaceous, coriaceous in texture, oboval, obtuse, shortly stalked, entire 

 in margin, and pinnate in venation. The stem above them is pubescent, and at a 

 short distance (about \ inch) up bears two leaves, which are trifoliolate and long- 

 stalked, the terminal leaflet being lanceolate, acuminate, and entire, the two lateral 

 shorter and toothed.^ Higher up ordinary pinnate leaves are borne. Plate 15 a 

 shows a seedling raised by Elwes from seed ripened on a tree overhanging Dr. Charles 

 Hooker's garden at Cirencester in 1900;'^ sown November 26, germinated under 

 glass in May 1901, and photographed on August 28 of the same year, when it 

 measured about a foot high ; the roots, which were very succulent and brittle, were 1 3 

 inches long. The seedlings were planted out in May 1902, and grew very rapidly, 

 attaining 5 feet in height, but did not ripen their wood, which was killed back in 

 some cases nearly to the ground. They are now (January 1905) 4-6 feet high. 



See Plate 14, fig. B. 



' As I know of no other tree in the neighbourhood this case seems to confirm Bunbury's observation that the tree in some 

 cases is capable of self-fertilisation. (H. J. E.) 



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