A deciduous tree 30 to 45 ft high, with a rounded head of branches and a trunk 6 ft in girth; young shoots downy at first, becoming more or less glabrous by autumn. Leaves broadly ovate with a heart-shaped base, usually pointed, sometimes rounded at the apex, frequently three-lobed, varying much in size, from 3 to 8 in. long and up to 6 in. wide, coarsely toothed, lightish green and only slightly roughened above, downy near the veins and midrib beneath; stalk 1⁄2 to 1 in. long. Flowers produced during May in the leaf-axils and at the base of the new shoots; females on stalked cylindrical spikes 1⁄3 to 1⁄2 in. long; male spikes longer. Fruit-clusters 1⁄2 to 1 in. long, white or pinkish, sweet, insipid.
Native of China, and possibly of other parts of temperate Asia; cultivated from time immemorial in many South European and Eastern countries. The white mulberry is the tree on which the silkworm is fed. It succeeds quite well in the south of England, but no success has ever been achieved in establishing the silkworm industry there in spite of several attempts, the first of which was made under the auspices of James I. The climate is considered to be too dull and damp. Nevertheless the tree is quite hardy at Kew; only succulent, over-vigorous shoots are injured by frost. The tree, however, lacks the quaint charm of the common mulberry.
There are three specimens of the white mulberry at Kew; one, near the rock garden, is 45 ft high, on two stems 61⁄2 and 5 ft in girth; and two in the Morus collection of 42 × 41⁄2 ft and 47 × 33⁄4 ft (1967). Others of note are: Shrublands Park, Ipswich, 40 × 73⁄4 ft at 1 ft (1968); Oxford Botanic Garden, pl. 1817, 45 × 63⁄4 ft (1970).
Many varieties of white mulberry are in cultivation, but those that differ chiefly in their influence on the silk produced by worms that feed on them have little interest to British arboriculturists. The following deserve mention:
cv. ‘Fegyvernekiana’. – A pigmy, usually under 3 ft high.
cv. ‘Laciniata’. – Leaves deeply lobed, the lobes narrow, pointed, deeply toothed (M. alba laciniata Beissn., not K. Koch; M. alba f. skeletoniana Schneid.).
cv. ‘Macrophylla’. – ‘This variety produces strong and vigorous shoots, and large leaves, sometimes measuring 8 in. long and 6 in. broad, resembling in form those of M. nigra, but smooth, glossy and succulent. The fruit is white’ (Loudon, Arb. et Frut. Brit., Vol. 3, p. 1349). The name M. alba macrophylla first appears in Loddiges’ Catalogue for 1836 and Loudon’s description was almost certainly based on a specimen in the Loddiges Arboretum. Under the botanical group name M. alba f. macrophylla (Loud.) Schneid., Rehder places as a synonym M. alba var. morettiana, but this mulberry (the Moretti or Dandolo mulberry) was completely distinct from the one offered by Loddiges under the epithet macrophylla as is clear from Loudon’s account (loc. cit.).
var. multicaulis (Perrotet) Loud. M. multicaulis Perrotet; M. alba var. latifolia Bur.; M. latifolia Poir. (?). – A large shrub, many-stemmed from the base and spreading by suckers. Leaves up to more than 1 ft long, concave beneath. Fruits almost black when fully ripe. Widely cultivated in China, whence it was introduced to France via the Philippines in 1821, by Perrotet. According to Loudon, this mulberry was easily raised from cuttings and propagated in large numbers by Italian and French nurseries. The plants cultivated in Europe may therefore be all of one clone. There is a specimen of this mulberry in the Edinburgh Botanic Garden, measuring 35 × 31⁄4 ft (1967). It was planted in 1906.
cv. ‘Pendula’. – A tree of very weeping habit forming an umbrella-like head. It is of so pendulous a nature that it is necessary to tie up a leading shoot every year to enable a trunk to be formed of the desired height. It should be trained up 20 ft, and will then make one of the most notable of weeping trees. There is an example 20 ft high at Talbot Manor, Norfolk.
cv. ‘Pyramidalis’. – of conical habit.
var. tatarica [Pall.] Ser. M. tatarica Pall. – Leaves smaller, up to 31⁄4 in. long. Fruits smaller.
f. venosa (Delile) Schelle M. alba var. venosa Delile. – Veins very conspicuous, yellowish. Possibly a clone.