A tree 60 to 100 ft high, with a rounded, spreading head of branches; the bark of the upper branches smooth and ash-coloured; young shoots without down. Leaves somewhat acrid-scented when rubbed, usually 8 to 12 in. long, on vigorous young growths 18 in., composed mostly of five or seven, sometimes nine, rarely eleven or thirteen leaflets. These are oval or ovate, shortly pointed, margins entire; terminal leaflet the largest, 3 to 6 in. long, the basal pair less than half the length and width; both surfaces glabrous except for small tufts of hair in the vein-axils beneath. Male catkins 2 to 4 in. long. Fruits green, glabrous, 11⁄2 to 2 in. across; nuts variously sculptured, with thick or thin shells.
The common walnut has been cultivated for so long and over such a wide area that its natural distribution is uncertain. But it and its subspecies (not treated here) are certainly native in S.E. Europe, in the forests south and east of the Black Sea, in the rain-forests of the Himalaya, N. Burma, and S.W. China, and in the mountains of Central Asia. The date of its introduction is not known, but it has existed in this country for many centuries. As an ornamental tree the common walnut is not so striking as several other species. It is chiefly grown for its nuts and for its soft, unripe fruits, which are made into a pickle. Its timber is a very valuable one, being perhaps the best obtainable for gunstocks. It is also largely used for furniture and veneering.
Because of the value of its timber the common walnut is rarely allowed to attain a venerable age, but there are specimens 60 to 80 ft high and 123⁄4 to 211⁄2 ft in girth in the following places (measurements made 1952-65, mostly by the late Maynard Greville): Little Sampford Hall, Essex; Laverstoke Park, Hants; West Suffolk Hospital, Thetford, Norf.; Grenville College, Stoke, Suff.; Gayhurst, Newport Pagnell, Bucks; Pilton Chase, Northants; Settrington, Malton, Yorks; Gordon Castle, Moray, Scotland.
Numerous variants of the common walnut have sprung up in cultivation and received names of botanical form. Some (especially those distinguished by their fruits) must have occurred regularly among seedlings. None, except ‘Laciniata’, is of any but historical interest:
cv. ‘Heterophylla’. – Leaflets long, narrow, irregularly lobed. The original tree was noticed in 1827 near Poitiers and propagated by grafting at the Royal Nurseries, Neuilly.
cv. ‘Laciniata’. – Leaflets cut into deep, narrow lobes. A handsome foliage tree, superior to ‘Heterophylla’. It arose early in the 19th century but seems to have been always scarce. The specimens recorded in the British Isles are all of much the same girth (4 to 51⁄4 ft) and are 35 to 52 ft in height, but must date from long after the original introduction. Their locations are: Melbury, Dorset; Westonbirt School, Glos.; Hergest Croft, Heref.; Lindon Park, Kent; Chilton Court, Caversham, Berks.
f. macrocarpa K. Koch J. regia var. maxima Loud. – Nuts about twice the ordinary size, but not good keepers and with kernels only half the size of the shell. Probably the same as the ‘Noyer à bijoux’ of the French, so-called because of the large shells being often mounted as jewel boxes. Also known as the Ban-nut or Claw-nut.
f. monophylla (C. DC.) Schneid. J. regia var. monophylla C. DC. – Leaflets reduced in number to a large terminal one and a pair of small ones, the latter often absent.
cv. ‘Pendula’. – This cultivar name belongs to a pendulous variety growing with the nurseryman Armand Gothier of Fontenay-aux-Roses, who brought it from Waterloo in Belgium in 1850 (Rev. Hort. (1853), p. 480). A small pendulous tree at Kew came from the nurseryman Lee of Hammersmith shortly before 1880.
f. prepaturiens (Pepin) Rehd. – The original plant was raised around 1830 by the French nurseryman Chatenay, of Doué, Maine-et-Loire, who found it bearing fruit in a bed of three-year-old seedlings. Its offspring by seed were said to be more or less true to type and bear fruit when less than 3 ft high (Rev. Hort. (1882), p. 419; Fl. d. S., Vol. 4, p. 367).
f. racemosa (C. DC.) Schneid. J. r. var. racemosa C. DC. – Fruits in clusters of ten to fifteen. Known in orchards as Cluster or ‘Noyer à grappe’.
f. rubra Hort. – Flesh of the kernel red, the skin blood-red; found wild in Styria and said to come true from seed. The name first appears in Wien. Ill. Gart. Zeit. (1897), p. 209 (an article by ‘A.C.R.’, probably A. C. Rosenthal).
f. fragilis K. Koch J. r. var. tenera Loud. – A curious variant known as the Thinshelled Walnut or Titmouse Walnut – the ‘Noyer à Coq tendre’ or ‘Noyer Mésange’ of French gardens. The shells are so thin that they are easily pierced by birds.
The varieties cultivated for the qualities of their fruit are beyond the scope of this work.