WILLOWS 



G.N. 6712 



WILLOWS 



Salix alba, caprcea, fragilis and ccerulea. Salicaceae. 



Light-coloured, diffuse-porous, pinkish-brown wood; very soft and 

 light in weight and very fine in the grain. 



Transverse section. Boundary vague yet clear with lens, sometimes 

 a line of parenchyma of flattened cells. 



Parenchyma not otherwise visible with lens (probably not present 

 except in the boundary line). 



Vessels extremely small, visible with lens, never with the naked eye: 

 diminishing in size a little on the outer side of the ring: scattered (or 

 sometimes in oblique lines as in the Birch, but much less pronounced) : 

 sub-divided groups numerous but short (rarely more than three pores 

 to the group). 



Rays visible with lens only : of one kind : regular in size and spacing at 

 intervals of the width of about a large vessel apart: almost too thin to 

 taper: of a rather darker shade than the wood. 



Radial section. Vessels visible yet very fine : rays just visible as minute, 

 brown, very narrow lines: boundaries traceable, clear, but not promi- 

 nent. Mr J. Line, of the School of Botany, believes that he has found a 

 distinction between Salix audPopulus in the number and shape of the pits 

 on the vessels at the point where the ray-cells form a cross-field. If this 

 is constant it will be a valuable and much needed adjunct (see below). 



Tangential section, as the radial, but the boundaries rather clearer as 

 loops: rays scarcely visible, uniseriate. 

 May be confused with : 



Lime, Birch, Sycamore, Tulip-tree 

 (all of these have multiseriate rays and 

 a colour which never approaches 

 pinkish-brown though it may be whitish 

 or brownish). 



Pear-tree and Alder (colour sometimes 

 pinkish -brown but rays multiseriate). 



Poplar (the heartwood of P. alba syn. 

 P. canescens, which is medium in 

 weight). 



P. fastigiata, tremula, nigra, i.e. the 

 white-wooded Poplars, and Horse 

 Chestnut. 



Poplars generally (two, sometimes 

 three rows of rounded pits in the cross- 

 fields of most of the ray-cells which are 

 all prostrate: constant?) 



Horse Chestnut: no distinction ex- 

 cept in size of elements, weight, colour, 

 etc. 5 to 8 rows of pits: ray cells all pros- 

 trate : spiral thickenings in the vessels. 



32 



May be distinguished by: 



Pinkish-brown colour and 

 uniseriate rays. 



Uniseriate rays : light 

 weight. 



Difference in weight, coarse- 

 ness of grain and hardness : no 

 other certain difference. 



Pinkish-brown colour : 

 other certain difference. 



no 



Willows generally (3-6 rows 

 of angular pits in the cross- 

 fields of the erect edge-cells 

 only: constant?) 



Pinkish-brown colour. Pits 

 as above. No spirally thick- 

 ened vessels. 



