Page:TheTreesOfGreatBritainAndIreland vol01.djvu/200

172 with the scale, its apex appears on the upper part of the scar as a minute reflexed point. Some of the scales are sterile; the others bear each two erect unequally three-angled seeds.

Taxodium is readily distinguishable in winter from other deciduous trees by the peculiar buds and branchlet scars which mark the twigs. The latter are very slender, terete, glabrous, and brown in colour, and bear at their apex the two pseudo-terminal buds described above, one of which, however, is often aborted in trees growing in England. Scattered over the twigs appear the branchlet scars and the lateral buds. The former are small circular depressions, surrounded by a slightly raised rim, and having a single dot or a minute protuberance in their centre. The lateral buds, also previously described, are smaller than the branchlet scars, and on twigs of one year arise just above the minute scars left by the primary leaves, in which a single dot may be made out with difficulty. Single-dotted leaf-scars occur in Larix and Pseudolarix; but in these genera branchlet scars are absent, and the twigs show spurs or short shoots, which are wanting in Taxodium.

The genus Taxodium was once common and widely distributed over the Holarctic region. During Miocene and Pliocene times it was spread over the interior of North America, throughout Europe, and in north-eastern Siberia. In the present day it is restricted to the Southern United States and Mexico.

The genus can only be confounded with Glyptostrobus, now represented by one living species, G. heterophyllus, Endlicher, a native of the province of Canton, in Southern China, where it occurs as a small tree along the banks of rivers and streams. Like Taxodium, it has deciduous foliage and branchlets. The leaves assume two forms—on ordinary branchlets long and linear and arranged in three rows, on fruiting branchlets closely imbricated, scale-like, concave internally and carinate externally. The cone, pyriform in shape, is composed of scales, which are not peltate, but elongated and arising from its base. The bract coalesces with the scale below; but above the middle is free and recurved, leaving bare the 5 to 7 lobed summit of the scale. The seeds, oblong or obovate, often short-spurred at the base, are narrowly winged on the sides and prolonged at the base into a flat, lancet-shaped wing. Glyptostrobus heterophyllus is not hardy at Kew, where specimens may be seen in the temperate house. A plant of it is reported to be growing in the open air at Castlewellan.