DOUGLAS FIR 



G.N. 8314 



DOUGLAS FIR 



Pseudo-Tsuga Douglasii Carr. Conifer. Abietine*. 



A moderately heavy, brownish -white wood, striped very broadly with 

 darker resinous-brown bands. It much resembles Larch and also the 

 darker sorts of Scots Fir from both of which it is difficult to distinguish 

 except with the microscope. Smell not resinous when worked, at least 

 when the wood is dry. It is rather unpleasant though not strong, and is 

 not revived by warming. Reaction with perchloride of iron, inky. The 

 resin remains fluid, the canals bleed and often stain the surface. 



Structure much resembling that of Pinus sylvestris. Must be observed 

 in thin section by the microscope. 



Vertical resin-canals abundant. Spiral thickening of the tracheids, 

 pronounced ? 



Horizontal resin-canals in tangential section stout and somewhat of 

 the outline of a boat (see Fig. 9). The canal in the middle height occupies 

 only a portion of the transverse diameter, i.e. there are one or two rows 

 of cells which separate it from the surrounding ground tissue. 



Pits in the cross-field, several, small, and slit-like. 



Pith small, about 1-5 mm. diameter. 



May be confused with: 



Scots Pine (one large pit in the 

 cross-field, slender rays in tangen- 

 tial section which contain a resin- 

 canal that occupies the whole 

 transverse diameter (compare Figs. 

 8, 9). No spiral thickenings in the 

 tracheids). 



Larch [rays as in Scots Fir, but 

 still more attenuated (compare 

 Figs. 8, 9). Spiral thickenings 

 rarely seen]. 



May be distinguished by: 



Two or several small pits in the 

 cross-field : wide rays in tangential 

 section with small resin-canal in 

 centre. Spiral thickenings usually 

 evident. 



As above. 



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