SALIX 473 



the other, and blur the dividing lines so completely as they do in Salix. 

 In Britain there are some seventeen or eighteen native species, every one 

 of which is considered to have hybridised with two or more of its fellows, 

 some with as many as nine. But whether, as is usually assumed, the 

 intermediates are always hybrids is doubtful. Willows generally do not, 

 in gardens at least, produce fertile seed so freely as to support the theory 

 of such multiple cross-breeding. It has to be said, however, that some 

 of these natural hybrids have been duplicated under cultivation by 

 artificial cross-fertilisation. 



Salix is a large genus of perhaps two hundred species of trees and 

 shrubs, all those hardy in Britain being deciduous or practically so. They 

 vary from stately timber trees of the type of S. alba and S. fragilis (80 ft. 

 or more high) to tiny shrubs like S. herbacea, creeping along the ground, 

 and only rising an inch or two above* it. The twigs of many species are 

 very tough, and the genus supplies vastly the greater part of the material 

 from which the baskets and vvickerwork of the world are made. 

 Although the twigs of several species have the ordinary toughness of 

 the genus, they are easily snapped off in their entirety at the point of 

 their union with the older branchlet. This curious characteristic is best 

 known in, and gives the popular name to, the crack willow (S. fragilis), 

 but there are several more that have it equally marked. The leaves of 

 willows are very variable : the typical shape is long and narrow, slender- 

 pointed, and toothed, but from that shape to an almost circular one there 

 is every gradation. In the remarkable S. magnifica, recently introduced 

 from W. China, the leaves are over 8 ins. long by over 5 ins. wide. Normally 

 they are alternate, although in S. purpurea it is quite usual to find opposite 

 ones as well. Stipules produced by willows are curiously variable both 

 in their size and persistence. They occur most markedly on the strongest 

 shoots, and are frequently entirely absent from weaker ones. 



It is the general rule for the sexes to be kept apart on separate 

 plants, a character which adds to the difficulty of distinguishing willows, 

 for the foliage and habit of male and female specimens of the same 

 species are not always identical. But this rule has occasional excep- 

 tions; some trees produce both sexes, sometimes on the same branch. 

 There is an example of S. MEDEMII, Boissier, at Kew, which frequently 

 has male and female flowers on the same catkin. Willow catkins vary 

 in shape, from cylindrical to egg-shaped, and are usually very silky-hairy. 

 The flowers, which are densely packed, have no sepals or petals ; the 

 male consists of a scale carrying two to five (sometimes eight or nine) 

 stamens ; the female consists of a scale bearing a single ovary. On the 

 opposite side of the stamens and ovary from the large scale, or sometimes 

 on both sides, is a small glandular scale, often called the "nectary." This 

 organ is relied on to afford distinctions in botanical books, but being too 

 minute for investigation by ordinary cultivators I have omitted considera- 

 tion of it in the following notes on the species. The fruit or seed-vessel 

 is a conical body splitting in two at the top, each half recurving when 

 ripe. Seeds minute, furnished at one end with a tuft of pale hairs. 



The flowers of willows are wind-fertilised, and appear usually in spring 

 on the naked shoots of the previous summer. They are not devoid of 

 II 2 H 



