Redwood cones are one inch or less in length. They ripen in one season. Seeds are quite small, and are equipped with wings. The bark is thick, but is much thinner than the bark of bigtrees, though it is in great ridges like the bark of that species. The habits of the two species, as to form of crown, are similar. Young redwoods, particularly if they grow in the open, develop symmetrical and conical crowns which they retain until the trunks are a foot or more in diameter. Lower limbs die and fall off after that, and old trees have crowns so small that it would seem impossible that they could supply the wood-building material for trunks so large. That the growth should be slow under such circumstances is to be expected. The ages of mature trees vary from 500 to 800 years, but an extreme age of 1,373 years is on record. The average is, therefore, considerably below that of bigtrees. Redwoods grow as tall as bigtrees, but do not equal them in diameter of trunk, though trees twenty feet in diameter occur. A noticeable feature of the forests is that, in a given stand, nearly all trees are of the same height, irrespective of size of trunk. The crowns go up to the light and when they reach the common level of others, and secure a share of light, they show no disposition to go higher. The doctrine which they silently put into practice is to live and let others live. That habit makes it possible for redwoods to grow in very dense stands, which they could not do if a few trees domineered over the others, and appropriated the light to themselves. When old age overtakes the giant redwoods, they exhibit the first symptoms of weakened vitality by dying at the top. Most trees over five hundred years old are “stag-headed.” From that period they die slowly, but usually survive two or three hundred years after the visible signs of approaching death strike them. Redwood has an advantage over nearly all other needle-leaf trees in that it propagates by both seeds and sprouts. Few softwoods send up sprouts from stumps or roots. Redwoods of large size are produced that way, and the stumps of very old trees send up many vigorous shoots. Sometimes a ring of large trees surrounds a depression in the ground where the parent tree grew, died, and decayed. Sprouts are of course confined to the immediate proximity of the parent tree, but redwood seeds are scattered by the wind over vacant spaces. This results in dense stands where other conditions are favorable, but the species has never been able to establish itself far inland or high on mountains.