Page:TheTreesOfGreatBritainAndIreland vol01.djvu/201



Three well-marked forms of Taxodium occur in the wild state, which differ in certain characters, such as the form of the foliage, its partial persistence or complete deciduousness, and the time of flowering; and in the present state of our knowledge these may be considered as constituting one species, the peculiarities mentioned appearing to depend on conditions of soil and climate, and to be by no means constant.

1. Var. typica. A tall tree, with a gradually tapering stem, which has an enlarged base, usually hollow internally and buttressed externally. When young it is strictly pyramidal in form; but in older trees the crown becomes wide and flattened, often 100 feet across, according to Sargent. The bark is dull reddish brown, 1 to 2 inches thick, fissured and separating into long fibrous scales. The leaves in this form are arranged pseudo-distichously on horizontally spreading branchlets, and are linear in shape (see generic description). This form is the one which occurs generally in the alluvial swamps of the southeastern United States.

2. Var. imbricaria.

A tree, generally smaller in size than the type, with branchlets normally erect, but occasionally somewhat spreading and very rarely pendulous. Leaves appressed on the branchlets and acicular-acuminate (see generic description).

According to Mohr, this is the "upland Cypress" which occurs on the shallow ponds of the pine-barrens and in semi-swampy woods on poor sandy soil. He considers it to be greatly inferior to the typical cypress of the alluvial swamps in regard to the size and quality of the wood; and states that in the earlier stages of its growth and on vigorous adventitious shoots it produces leaves of the ordinary form. It passes readily, according to his observations, into the type, where the soil conditions are favourable. He considers the peculiarity of the foliage to be an adaptation to check excessive transpiration during the time of drought when the sandy soil is laid bare to the sun and the supply of water diminishes.