COMMON ELM G.N. 6582 



COMMON ELM 



Ulmus campestris Linn. Ulmacese. 



A rather hard, heavy, ring-porous wood of a brown colour striped with 

 darker brown (the pore-rings) and a prominent silver-grain of narrow, 

 brown flakes. A heartwood-tree. Sapwood narrow. Wood resistant to 

 splitting. 



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

 parenchyma. Contour sub-regular. 



Parenchyma (a) abundant around the vessels (vasicentric), extending 

 laterally or obliquely and joining up the vessels to concentric or oblique 

 lines (in very wide rings of quickly-grown wood, the parenchyma (a) in 

 the Spring zones may however be scarcely more than sheaths around the 

 vessels). 



Vessels of the pore-ring readily visible, of two to three rows. Those 

 of the Autumn wood in concentric wavy, nearly continuous lines that 

 become flatter as they approach the outer boundary. The lines in wide 

 rings are at first very oblique. The vessels are single or in radial, sub- 

 divided pairs and threes or more. 



Rays sometimes visible when dry, always when wet : irregular in size, 

 but sub-regular in spacing, at intervals from about the width of a vessel 

 apart, to twice that distance. 



Radial section. Boundaries (the pore-rings), very prominent, between 

 which are seen fine brown lines which are practically continuous (i.e. lines 

 of Autumn vessels). These may be full of thyloses which are spherical 

 not flattened. Spirally thickened fibres abundant and clear (microscope). 



Tangential section. As the radial but the rays are extremely minute. 

 By reason of their numbers and dark colour, they produce a half-tone 

 effect that imparts a very soft appearance to the surface of the wood. 

 In the Autumn wood, a pretty zigzag tracery is seen within the coarsely- 

 fringed loops. When viewed by the microscope in tangential section, the 

 rays have the contour of a broad-beamed boat (Fig. 10). 



The light-brown watery extract gives a brown precipitate with per- 

 chloride of iron ; it does not turn inky. 

 May be confused with: May be distinguished by: 



Other Elms such as Wych Elm Its capacity for the holding of 

 [hard to work; rays in tangential nails and easy working. Rays in 

 section narrow of the form of a tangential section dark, but pro- 

 racing " eight " (Fig. 11). Re- ducing a pronounced half-tone 

 action with perchloride of iron, effect and under the microscope 

 golden, no precipitate (constant ?)] . they appear as stout bodies having 

 Spirally thickened fibres rare and the outline of a steamer (Fig. 10). 

 obscure. Reaction slight, brown precipitate. 



Spiral fibres abundant and clear. 



s. 17 2 



