i8 



THE WYCH ELM {ULMUS MONTANA). 



}' . CJ . K E E G A N , L I, . D . , 

 Patterd<iU, Westmoilaiui. 



Among the prehistoric trees specially characteristic of the Lake 

 District is the Wych or Mountain Elm. It may be deemed and 

 termed an opportunist sylvan item in that locality, i.e., the 

 soil and situation thereof are admirably adapted to the secure 

 ensconcement and vig^orous development of the tree. Rich, 

 deep, loose alluvial bottoms, lavishly paved with rock-debris, 

 and therefore of infirm texture, and almost constantly drippinij 

 with percolating- water, supply an excellent medium for the 

 penetration of its long tough roots, capable of fully ministering 

 to its inorganic needs. The fact that some such adaptive rela- 

 tions between soil and organism are indispensable in the case of 

 this particular tree will be evinced in the course of the following 

 exposition of its chief anatomical, chemical, and physiological 

 characteristics. 



Stem. — The wood is moderately hard and heavy (specific 

 gravity 0.628), lightish-brown in colour, with a fairly clear 

 distinction between alburnum and duramen. The medullary 

 rays occur singly or are grouped in three or four layers, and in 

 tangential section may be twelve times longer than broad ; the 

 vessels of the spring wood are very large, being over 160 /a wide, 

 have areolated pores, and form a continuous belt of one or two 

 rows, but in the autumn wood they are much narrower, have 

 areolated pores and fine spiral bandlets, and are arranged in 

 narrow, wavy, concentric bands ; the very thick-walled fibres 

 occupy most of the interspaces between the vessels, while the 

 parenchyma is sparsely distributed among" the smaller vessels. 

 In the bark, the long, smooth, poorly-lignified fibres are 

 arranged in bundles which form irregular concentric zones, 

 separated laterally by the soft bast, which consists of cells 

 enclosing either a single crystal or a red-brown pigment, and of 

 sieve-tubes which are united end to end by transverse partitions 

 nearly the whole svuface of which is a simple sieve ; isolated 

 bast-fibre bundles occur in the pericycle, i.e., the latter is dis- 

 continuous ; the phellogen is the sub-epidermal layer, and the 

 superficial periderm formed thereby lasts three or four years, 

 atter which the secondary periderm and a persistent rhytidome 

 commence to be produced in the form of flattish scales, tin- 

 ext(;rior parts of stem and branch ultimately becoming more or 



.Naturalist, 



