AMERICAN ELM 



O.N. 6582 



ELM (AMERICAN) 



Ulmus americana Linn. Ulmacese. 



A moderately hard and heavy, ring-porous wood of a pale brownish- 

 white, cane-like colour: not much resembling English Elm. Structure 

 badly developed in most rings, as little Autumn wood is produced. 



Transverse section. Boundary, the pore-ring compacted by much 

 parenchyma (a) of a light colour, which almost smothers the pores and 

 greatly affects the colour of the section. The parenchyma occupies half 

 or more of the transverse surface. 



Vessels of the pore-ring usually of one row only. Those of the Autumn 

 wood much smaller and joined up into very delicate, light-coloured, 

 concentric wavy lines. 



Radial section. Silver-grain pale and inconspicuous. 



Tangential section. Rays difficult to see even with the lens: no half- 

 tone effect produced. Grain rather fine. Other characters much as in 

 the Common Elm which should be compared. 



Ulmus racemosa Thomas, the Rock Elm, is similar to the above but 

 generally of slower growth. 



May be confused with: 



Common Elm (pore-ring of 

 several rows of pores: coarse tex- 

 ture : surface very soft-looking from 

 the half-tone effect produced by 

 the brown rays in tangential sec- 

 tion). 



Wych Elm (fast-grown, pore- 

 ring of two or more rows except 

 in badly developed rings. Silver- 

 grain clear. Parenchyma an ex- 

 tremely small proportion of the 

 area). 



May be distinguished by: 



A one-rowed pore-ring, fine 

 cane-like texture: no half-tone. 



Slow-grown: pore-ring rarely if 

 ever of more than one row even 

 in well-developed rings. 



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