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178 analogous to the cone-shaped base of the former; and from Coulter's observations it would appear that seedlings of Taxodium are also rare here, and that it is being beaten in the struggle by the Nyssa, the seedlings of which are very abundant.

A disease due to a fungus has attacked many of the trees in the Mississippi valley; the heartwood is found when the trees are cut down to be full of holes ¼ to ¾ inch in diameter.

Taxodium is one of the most striking and characteristic trees in the Gulf States, having its branches often covered with Tillandsia usneoides, the "Spanish moss" of the inhabitants, the long grey masses of which wave in the wind and give it a strange appearance. The trunk takes many curious forms, which seem to be induced by the nature of the soil and the depth of the water, sometimes branching low and surrounded by buttresses, sometimes growing straight up to a considerable height (Plates 52–53). From the stout wide-spreading roots arise woody cylindrical projections, sometimes above a foot in diameter and 5 to 7 feet high, which are called "cypress knees." The growth and functions of these have been the source of much discussion. Berkeley supposed that they serve to aerate the submerged roots; others have thought that they help to anchor the roots in soft muddy soil. As the knees, however, occur to some extent even on ground which is never flooded, as in the trees at Syon, these suppositions, though highly probable, must remain somewhat doubtful.

The knees are hollow inside, and smooth externally, being covered with a reddish, soft, and spongy bark. They never show any sign of vegetation, and will not put forth shoots, even if wounded and covered with earth.

In England the Taxodium grows much better than might be expected considering how much colder and shorter are our summers than those of its native country. It was introduced by John Tradescant about 1640, and described by Parkinson as Cupressus americana.

For some unexplained reason it has lost the popularity it once enjoyed, and is now seldom planted, though it grows well in the southern and western counties. I have raised it from American seed, which, however, must be soaked in warm water for some time, and placed in a warm house to get good results. It grows rapidly at first, but as the young wood is not ripened, and no terminal bud formed (which