KNOBTHORN 



Alternative Name. Knob-hout. 



Physical Characters, etc. Recorded dry-weight 44I-4SJ lbs. 

 per cu. ft. Hardness, Grade 7, compare English Alder. Smell 

 and taste none. Burns moderately well with a noisy, crackling 

 flame and a rather pleasant aroma : embers glow in still air. 



Grain. Very fine and compact. Surface brilliant. 



Bark. Light brown, about f inch thick, covered with lighter- 

 coloured papillae (lenticels) and also having prominent, corky 

 excrescences, hence the popular name. Closely adherent and 

 compact. There is a lentical upon the apex of each of the 

 " knobs." 



Uses, etc. " Timber 10-12 inches in diameter, heavy, close- 

 grained and hard . . . axles, yokes, tools, etc." (19). 



Authorities. Charpentier (21), p. 136. Nordlinger (86), 

 vol. vii. p. 53. Cape Land Almanac (19). 



Colour. Heart-wood excentric, brown, well defined from the 

 greenish-yellow sap-wood which is about 2-3 inches wide. 

 " Greenish-yellow " (86). 



Anatomical Characters. Transverse section : — 



Pores. Need lens, size 3-4, very uniform : evenly scattered 

 throughout the ring : single or in short radial groups of 2-4, 

 closely pressed between the rays : few 15-30 per mm. 



Rays. Just visible to good sight size ; 5-6, uniform : tapering 

 to fine ends : weak, slightly avoiding the pores : 7-11 per mm. 

 rather less than a pore-width apart : of lighter colour than the 

 ground-tissue. 



Rings. Clear : the boundary a very fine, light-coloured line 

 of regular contour. The much more prominent smoky zones 

 of irregular contour must not be taken to be the boundaries, 

 as they are quite independent of the structure. 



Soft-tissue. Very narrowly encircling the pores and may be 

 overlooked : perhaps also the boundary lines. 



Pith. ? 



Radial Section. Pores very fine, shining scratches.. Rays just 

 visible as narrow lines upon a cleft surface by contrast of lustre. 

 The pigment-zones are clear but less prominent and the true 

 boundary clearer than in the transverse section. 



Tangential Section. As the Radial, but the rays need lens and 

 are fine, clearly-cut lines about 0.5 mm. high. The true boundary 

 is even prominent in this section as yellowish or brown loops and 

 lines. 



Type, specimen authenticated by the Forest Officer to the 

 Government at Natal. 



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