in 1904 as 60 feet by 8 feet. At Grignon,!a tree resisted without injury the low temperature of — 23° cent. in the winter of 1870-1871; and in 1879-1880, when the thermometer fell to — 26° cent., it only lost a few of its branches. (A.H.)
ACER INSIGNE
- Acer insigne, Boissier et Buhse, Aufzähl. Transkaukas., 46 (1860); Boissier, Flora Orientalis, i. 947 (1867) ; Masters, Gard. Chron. x. 189, f. 24 (1891).
A large tree; bark of young stems dark grey, smooth, and marked with longi- tudinal whitish lines. Young branchlets glabrous, green, becoming dark reddish in autumn. Leaves (Plate 206, Fig. 18) resembling those of A. Pseudoplatanus in form and size, scarcely exceeding 6 inches wide and 7 inches long, but usually with some- what shorter lobes, acute or acuminate; serrations and teeth more rounded than in the sycamore; under surface pale in colour, scarcely glaucous, with loose white or brown pubescence, dense along the sides of the primary and secondary nerves, forming tufts in the axils, and scattered over the surface between the nerves.
Flowers, very distinct from those of A. Pseudoplatanus, in erect many-flowered terminal corymbs, appearing with the leaves, small, greenish; bracteoles minute, about 1⁄50 inch; filaments glabrous. Fruit, ripening in autumn; keys 1½ to 2 inches long; carpels brown, pubescent on the upper side; wings broad, divergent at an angle of 45°.
In the absence of flowers or fruit, this species is best distinguishable from the sycamore by the buds, which are long and sharp-pointed, with eight to ten external scales, ciliate in margin and with a tuft of pubescence at the tip ; lateral buds plainly stalked, arising from the twigs at an acute angle; opposite leaf-scars not joined round the twig, which is glabrous throughout.
Boissier considered that there were two forms of the species growing wild:—var. velutina, with leaves velvety pubescent beneath ; and var. glabrescens, with glabrous leaves. Bornmüller,” who studied the tree, while collecting in Persia, is of opinion that these varieties are unstable, as the amount of pubescence is variable ; and all the specimens in the Kew herbarium are more or less pubescent. (A.H.)
Acer insigne was discovered by Buhse in the eastern Caucasus, in the moun- tains of Talysch, where, according to Radde,’ it is common in the forests from sea- level to 2000 feet altitude, and grows to a large size, developing a wide crown of foliage on good soil, and thriving best in moist situations. It is also recorded by Radde from the valley of the Alasan river in the central Caucasus. It grows
1 Mouillefert, Essences Forestières, 214 (1903). Cf. also Actes Premier Congrès Internat. Bot. 385 (1900), where it is stated that this species sustained at Paris without injury the severe winters of 1879–1880 and 1890–1891.
2 Bull. Herb. Boissier, v. 643 (1905). Bornmüller recognises three varieties, based on the shape of the leaf :—typica, Bornmüller, lobes of the leaf acute or acuminate ; obtusiloba, Freyn et Sint., Bull. Herb. Boissier, iii. 843 (1902), lobes obtuse ; and longiloba, Bornmüller, lobes three, elongated, acuminate.
3 Pflanzenverb. Kaukasusländ. 184 (1899).
