Page:TheTreesOfGreatBritainAndIreland vol02B.djvu/133

Rh

The form of this species usually cultivated in England is distinguished in summer by its small leaves, bushy habit, and the other characters given above. In winter the following characters are available:—Twigs very slender, olive-green or brown, densely pubescent. Leaf-scars set obliquely on prominent pulvini, small, obcordate, notched above, without pubescent band above the upper margin; bundle-dots in three groups. Terminal bud elongated, slender, densely and minutely pubescent, the tips of the two outer scales slightly lobed. Lateral buds, arising at an angle of 45°, minute, ovoid, pubescent, usually solitary. Pith small, brownish, with wide chambers.

According to Sargent this species occurs on the limestone banks of the streams of central and western Texas, shrubby or rarely more than 30 feet high (var. typica); common and of larger size in the cañons of the mountains of New Mexico and Arizona south of the Colorado plateau. It is also met with in northern Mexico, where it frequently leaves the mountain cañons, following the water-courses which are dry throughout most of the year. In such situations its average diameter is 12 to 18 inches, and its height 20 to 30 feet; the nuts, less than an inch in diameter, are scarcely edible.

This species was discovered in western Texas in 1835 by Berlandier. It was growing in 1868 in the Botanic Garden at Berlin, according to a note in Engelmann's Herbarium. It does not seem to have been known in England till 1894, when seeds from Fort Huancha in Arizona were sent to Kew by Sargent. A tree grown from this seed has attained now (1905) about 12 feet in height. There is one nearly as large at Tortworth, and a seedling from Kew is planted at Colesborne, where it seems at least as hardy as the common species and ripens its wood earlier. A tree planted at Mount Edgcumbe, near Plymouth, in 1898 is 9 feet 4 inches high, with a spread of 10 feet. It has been cut back twice, and looks better as a bush than as a tree.