The willows and the cottonwoods belong to the same family of trees, _Salicaceæ_, and the family is fairly numerous, and it has some well-defined traits of character. The quinine-bitter of the bark is ever present, but more marked in willows than in cottonwoods. Though quite unpleasant to the taste, it is harmless. The leaves never grow in pairs, and in most instances they fall early in autumn, and some without changing color. Male and female flowers are borne on different trees, and fertilizing is done by insects, often by honey bees and bumblebees. Fruit ripens in late spring, and the seeds are equipped for flight by being provided with exceedingly fine silky hairs. The wind carries them long distances. The trees generally grow in the immediate vicinity of streams or in situations where the soil is damp, but there are exceptions. The willow family consists of two genera, one the cottonwoods or poplars, the other the willows proper. There are about seventy-five species of willow in America, twenty of them trees. Some, however, are quite small and only occasionally attain sizes which place them in the tree class. The willows are old residents of this continent. They grew in the central portion of what is now the United States in the Cretaceous age, as is proved by their leaf prints in the rocks. They have held their ground ever since, and there is no likelihood that they are about to give it up. Few species are better fitted for holding what they have. A few trees are capable of seeding a large region in a few years, and if soil and situation are suitable, reproduction will be abundant. The willows’ tenacity of life is often remarkable. It sometimes seems next to impossible to kill them by cutting off their tops. There are said to be instances in Europe where willows have been pollarded successively during hundreds of years, the crops of sprouts being used for wickerwork and other purposes. No such records exist in this country, but the willow’s sprouting habit is well known. A shoot stuck in the ground will grow, and a fence post will sprout. Many willows develop large stools, or roots, and repeatedly send up numerous sprouts, and it makes little difference how often they are cut, others will come up. Comparatively few willows that start in life ever become trees. They are suppressed by crowding, or meet misfortunes of one kind or another which keep them small, but occasionally a tree of good size results. Willow trees are usually not old. Probably few reach an age exceeding 150 years. Large trunks, in old age, are apt to be hollow or otherwise defective, though a willow tree will live many years after much of its trunk has disappeared. A little green bark on the side, and sprouts from the stump will maintain life long after all usefulness has ceased.