A large deciduous tree, ultimately 80 to 100 ft high, usually much less in this country, and branching low down, forming a wide-spreading head; trunk of large trees 10 to 12 ft in girth, with deeply furrowed bark; ends of young shoots minutely scurfy. Leaves 8 to 18 in. (sometimes over 2 ft) long, composed of from three and a half to thirteen and a half pairs of leaflets; these are stalkless, oblong, obliquely rounded at the base, pointed, toothed, normally 2 to 41⁄2 in. long by 3⁄4 to 13⁄4 in. wide (occasionally, on vigorous shoots, 8 or 9 in. long); dark green, glabrous and glossy above, tufted with stellate hairs along the midrib beneath; common stalk round. Male catkins 3 to 5 in. long, cylindrical, the flowers closely packed. Female catkins 12 to 20 in. long, with the flowers scattered, afterwards developing nuts which, with the wings, are 3⁄4 in. in diameter, roundish, oblique, horned at the top.
Native of the Caucasus and N. Persia, inhabiting moist places. It was introduced to France by the elder Michaux, who took back seeds from Persia in 1782. This tree likes a rich soil and abundant moisture, and whilst the fine specimens mentioned below show that it will thrive very well in the south of England, it loves more sunshine than our climate affords. The lover of trees will find nothing more interesting in and around Vienna than the magnificent examples of Pterocarya fraxinifolia. There, of course, the summers are much hotter, and the winters colder than ours; the tree bears fruit freely even in this country, and is very attractive in late summer when hung with the long slender catkins.
In previous editions a tree at Melbury Park, Dorset, was mentioned, which early this century measured 90 × 12 ft. It is now 105 × 171⁄2 ft (1972) and there are three others there 75-88 ft high, 131⁄2-15 ft in girth. Other examples are: Hyde Park, London, 58 × 103⁄4 ft (1967); Syon House, London, 67 × 111⁄4 ft (1967); Frensham Hall, Haslemere, pl. 1905, 70 × 73⁄4 ft (1968); Abbotsbury, Dorset, 115 × 12 ft (1972); University Botanic Garden, Cambridge, a huge many-stemmed bush 85 ft high, the largest stem 10 ft in girth (1969); Clare College, Cambridge, 70 × 163⁄4 ft at 2 ft (1969).
var. dumosa Schneid. P. dumosa Lav., nom. – A shrubby variety of dwarf habit, with small leaflets 2 or 3 in. long. Although first noticed in the Arboretum at Segrez, in France, this is apparently a truly wild form, judging by the following statement of Jean Van Volxem:
‘The country around Lagodechi (in the Caucasus) is very interesting. Near the river are extensive swamps, where I saw P. caucasica growing sometimes as an enormous tree, sometimes as a large shrubby bush. The two forms are intermixed with each other, so that no condition of soil or exposure can explain the fact, and there is, as far as I saw, no intermediate form, and I could detect no difference between the two forms except as to habit and size.’ (Gardeners’ Chronicle, Vol. 7 (1877), p. 72.)