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orbicular, denticulate, emarginate with a long slender mucro. Seed ¼ inch long, with dark purplish shining wings, which vary in length according to the height of the scale which they cover almost completely.

Var. arizonica, Lemmon, Bull. Sierra Club, ii. 167 (1897); Masters, Gard. Chron. xxix. 86, 134, ff. 52, 53 (1901).

Abies arizonica, Merriam, Proc. Biol. Soc. Wash. x. 115, ff. 24, 25 (1896); Purpus, Gartenwelt, V. 4, 26 (1896).

This form occurs in the San Francisco mountains in Arizona, where it is common between 8500 and 9500 feet elevation, and occasionally ascends to 12,000 feet. It is remarkable for the creamy-white thick corky bark of the trunk. As seen in cultivation, young plants differ from the type, in the leaves being emarginate at the apex, whiter beneath, and more regularly pectinate in arrangement. Sargent! states that bark equally corky occurs in trees of Abies lasiocarpa in other regions, as in Colorado, Oregon, South Alberta, and British Columbia; and, as there is no difference in the cones, he does not assign even varietal rank to the Arizona tree.

The best account of this variety is by Prof. Purpus in Mitt. D. D. Ges., No. 13, Pp. 47 (1904), who visited the San Francisco mountains in 1901, and introduced the tree to Europe. It seems to be a strictly alpine tree, growing on basaltic and trachytic rocks, where the soil is never quite dry, either scattered or mixed with Populus tremuloides, Pinus flexilis, Pseudotsuga Douglasii, and Picea Engelmanni. It attains a height of 60 to 70 feet with a girth of 6 to 9 feet. The bark is very corky and corrugated, in old trees milk-white or silver-grey in colour. It is replaced in these mountains at 7000 to 8000 feet by Abies concolor.

This form has only recently been introduced into cultivation. Plants were for sale in the Pinehurst Nurseries, North Carolina, in 1901; and Dr. Masters saw a stock of young plants in Moser’s nursery at Versailles in 1903. It is too soon yet to form any opinion as to the suitability of this variety for ornamental gardening.

Abies lasiocarpa is perhaps most readily distinguished by the conspicuous bands of stomata on the upper surface of the leaf, which separate it clearly from the other species * with median resin-canals and long narrow leaves. The following points are also noteworthy:—the irregular arrangement of the leaves, which are usually quite

entire at the apex; the ashy-grey pubescent shoots ; and the resinous obtuse buds. (A.H.)

This is essentially the alpine fir of the Rocky Mountains and higher ranges on the west coast of North America, and is the most widely distributed fir of the New World, occurring from about lat. 61° N. in Alaska to Arizona and New Mexico. It does not occur in California.* In the west it extends to the summits of the Olympic

1 Silva, xii, 113.

2 As A. sibirica and A. sachalinensis, which it somewhat resembles in general appearance,

3 U.S. Forest Service, Sylvical Leaflet 1, Alpine Fir.