258 TIMBERS AND THEIR USES 



any plant may be classed as timber it must be 

 present in greater quantity ; it is hard to give 

 an exact definition of a timber tree, but the 

 Hazel may be taken as approximately the 

 minimum size of a timber-bearing tree. 



The function of wood is mainly a mechanical 

 one — it acts as a support to the growing 

 stem, holds the branches in position and, ex- 

 cept in rare cases, keeps the plant in an erect 

 position. 



All the flowering plants are or with age may 

 become woody — such flowering plants are known 

 as Phanerogams. The Phanerogams again are 

 divided into two great groups or divisions ; the 

 Gymnosperms, or plants with naked seeds, and 

 the Angiosperms, or plants with covered seeds. 

 The latter are further divided into two classes, 

 the Monocotyledons, plants with a single seed 

 leaf or cotyledon and Dicotyledons, plants with 

 two seed leaves or cotyledons. Of the Gym- 

 nosperms, trees of the Natural Order Conifer cb 

 are also useful for timber. All the members 

 of this order bear cones, which in reality are 

 overlapping scales on which the seeds are borne. 

 Their leaves, with the exception of those of the 

 Maidenhair Tree, are needle-like, their wood is 

 soft and resinous. There are exceptions to this 

 rule, however, for the Yew and Maidenhair Tree 

 do not have cones, and the former is not resinous; 



