WALNUT G.N. 6696 



WALNUT 



Juglans regia Linn. Juglandacese. 



A feeble or bastard-ring-porous wood of a characteristic neutral-brown 

 colour to which it gives its name : often striped with blackish lines. The 

 grain (exposed vessels) has black linings also. Rather hard and heavy. 

 A heartwood tree. Sapwood whitish or ecru. 



Transverse section. Boundary a line of contrast in the density of 

 succeeding rings or often a thin band of denser tissue along which are 

 found a loose row of large vessels. 



Parenchyma of two sorts (a) very scanty, vasicentric, not visible 

 with lens ; (b) in minute bars, very fine, generally visible in the Autumn 

 /one (needs lens and careful search, being difficult to see even with 

 microscope in this section and needs oblique light. To make sure that 

 the nature of this tissue is properly grasped, the student should 

 compare the Hickory in which this parenchyma (b) is visible with the 

 naked eye). There is also some parenchyma dispersed amongst the fibres. 



Vessels just visible, rather large, very few and widely isolated, often 

 twinned or in radial threes and fours. The vessels diminish gradually 

 in size outwards to the boundary. 



Rays very fine, multiseriate, regular in size, but rather irregular in 

 spacing, at intervals from the width of a vessel apart, to double that 

 distance: brown, lighter in colour than the ground. 



Radial section. Boundaries somewhat indefinite. Vessels rather coarse, 

 black or blackish within. Rays just visible as a half-tone effect. 



Tangential section. As the radial, but the boundaries appear as coarse, 

 but thinly-fringed loops frequently accompanied by a paler zone corre- 

 sponding to the Spring wood. Rays need lens, but by their numbers and 

 colour, impart a soft tone to the surface. 



May be confused with: May be distinguished by: 



The heartwood of Hickory Parenchyma (b) very difficult to 



[parenchyma (b) very clear and see (lens). Pore-ring loose and 



light-coloured. Pore-ring loose but made evident by the light-coloured 



very prominent]. tissue around the pores rather than 



by the pores themselves. 



Red Gum or Satin Walnut [pores Pores very large and widely 



very small and crowded (lens), and isolated, becoming rapidly smaller 



indistinguishable with unaided eye towards the outer boundary of the 



on plank face. Wood soft and ring. On plank face they appear 



light]. as shiny, black-lined grooves. 



Wood hard and heavy. 



American Black Walnut (J. nigra Colour tending to drab-brown, 



Linn.), colour tending to purplish- grain usually curly: no certain dis- 



brown, grain usually straight. tinction. 



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