CHAP. XI.] SALICACE^. 181 



is either not furrowed, or very slightly so; but it 

 has four angles which are more or less distinct 

 in the different species : the shell and the dissepi- 

 ments are both very hard, and the latter, as in 

 the Mocker nut, are sometimes entire, so as to 

 render it very difficult to extract the kernel. 

 The leaves (c) resemble those of the walnut ; 

 but they are generally of a thinner texture, 

 and somewhat downy, the down being disposed 

 in little tufts, as may be seen by a microscope. 

 The trees vary much in size, but all of them 

 have a reticulated bark. The wood is of a coarse 

 grain, and will not polish ; but it is very strong, 

 and so remarkably tough that it is hardly possible 

 to break it. 



There is only one other genus in the order 

 Juglandacese, and that consists of only a single 

 species, Pterocarya caucasica. It has pinnate 

 leaves of nineteen leaflets each, placed as closely 

 as possible together; and the fruit, (that is, the 

 husk,) is spread out on each side into a thin 

 membrane or wing. This plant is sometimes 

 called Juglans fraxinifolia. 



SALICACE.^.— THE WILLOW TRIBE. 



The plants contained in this order have 

 simple leaves, and the male and female flowers 



