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174 Harper considers this variety to be a distinct species, and in support of this opinion alleges that certain differences which he has observed in the two forms are constant. The bark in var. imbricaria, both in cultivated and wild specimens, is considerably thicker and more coarsely ridged than in the typical form. The enlargement of the base of the trunk is abrupt in the former, conical in the latter. Knees are formed more abundantly in trees of the type, and are usually slender and acute, sometimes reaching a height of 6 feet. In var. imbricaria the knees are short and rounded, often almost hemispherical in shape. The type is a lover of limestone, the variety just the opposite. The distribution of the two forms is different, dependent upon the geological nature of the soil, var. imbricaria always growing on the Lafayette formation, which is a deposit of sandy clay, while the type always occurs on other formations. Harper admits the occurrence of intermediate forms, but states that they are rare. He has records of 300 to 400 stations in Georgia for var. imbricaria, at each of which there may be from ten to several thousand trees, while he has only seen intermediate forms about twenty times, and never more than 100 trees at one station. In the intermediate forms branchlets with distichous leaves occur on young shoots. Harper has seen in Georgia specimens of var. imbricaria as large as the ordinary form; but it is generally admitted to be a smaller tree. The two forms often grow close together, but in different situations. On the Savilla river in Camden County, Georgia, he noticed the type growing along the water's edge below the Lafayette formation, while a hundred yards or so away var. imbricaria was flourishing in moist pine-barrens.

Var. imbricaria is possibly a juvenile form, analogous to Cryptomeria elegans. The generally smaller size of the trees and the various differences noted by Harper are probably the result of poor soil, and do not, in my opinion, entitle this form to rank as a distinct species.

This variety was early introduced into England, as it was in cultivation, according to Aiton, at Kew in 1789. The original tree at Kew, now dead, was living in 1886, when it was described by Sir Joseph Hooker as 40 feet in height and of remarkable habit, on account of its slender twisted stem with decurved branches and pectinately-disposed branchlets. A small tree, 20 feet in height, is now growing in Kew Gardens.

A tree of the Mexican kind was reported to be growing at Penrhyn Castle, North Wales; but Elwes saw it in 1906, and confirms the opinion I had formed from specimens sent by Mr. Richards, that it is var. imbricaria. It is 44 feet high and 4 in girth, and comes into leaf later than the ordinary form growing near it.

At Pencarrow, Cornwall, there is a fine specimen, which was planted about 1841 by Sir W. Molesworth. It had attained in 1899 a height of over 30 feet, with a girth of stem of 2 feet 9½ inches at 5 feet from the ground.