A certain botanist of distinction being consulted by an amateur about some variety of willow exclaimed: "Pray, don't tempt me among the willows; that way lies madness!" They are, indeed, a most complex family, consisting of no fewer than one hundred and sixty recognised species, besides those chance hybrids which, being not only wind-fertilised, but dioecious (that is, the male and female inflorescence is borne on separate trees), they are so prone to produce. Bentham and Hooker admitted fifteen species as indigenous to the United Kingdom, ranging from _Salix herbacea_, dwarfest of British shrubs, humbly crouching on bleak mountain crests and seldom rearing its fairy branchlets to a greater height than a couple of inches, to the massive white willow (_S. alba_), which may tower to the height of nearly 100 feet. British foresters have not hitherto turned the capabilities of the better kinds of willow to such account as might be done, for, except in the osier industry and for the manufacture of cricket bats, willows are scarcely ever cultivated for profit. When they are planted at all they are generally shoved into some piece of sour, swampy ground, fit for nothing else; and the fact that they will actually flourish in such places is taken as evidence that they prefer them. But the better willows appreciate a kindly soil as much as any other tree, and it is only on wholesome, but moist, land that they develop their proper qualities. By far the most valuable willow in the present condition of the timber market is the blue willow, which some botanists distinguish as a species under the name of _Salix coerulea_, but which is more generally deemed to be a hybrid between the white willow (_S. alba_) and the crack willow (_S. fragilis_). It is easily distinguished from both its reputed ancestors; first, by its habit, which is far more erect than that of the others, all the branches ascending without any tendency to spread or droop; second, by its leaves, which are not nearly so downy as those of the white willow, and of thinner texture, so that, when one is held up against the light the tertiary venation may be seen through a lens to be translucent; and, third, by the bark, which is quite different from the rugged covering of the crack willow, and much smoother than that of the white willow. The fissures or seams in the bark are straight and set close together, enabling one to distinguish the blue willow from all other kinds at all seasons. The general tone of the foliage is silvery blue, instead of the silvery grey of the white willow.