STEMS. 23 



in thickness, shape, and texture. Its thickness is generally 

 in proportion to the age of the plant ; though some species, 

 gums for instance, shed their bark yearly. The outer bark 

 is the epidermis ; the fibrous inner layer is the liber or bast. 

 Many kinds of bark are of great commercial and medicinal 

 value. That of wattles is very highly esteemed for tanning ; 

 that of gums, tea-trees, Pimeleas, and other Australian 

 plants for paper-making, oils, resins, dyes, ropes, etc. 



Branches are lateral {growing from the side) additions to 

 the principal stem. Generally speaking, they are either 

 erect, horizontal, or pendulous. In some trees, as in the 

 Araucarias, — Norfolk pine, bunya-bunya, and Moreton Bay 

 pine, — they grow in whorls or parts arranged at the same 

 level round the stem, in a manner resembling the radiation 

 of the spokes of a wheel. Some trees shed their branches. 

 The principal branches are limbs, the smaller ones branchlets 

 and twigs. Some stems and branches are armed with 

 spines or thorns ; others have glandular hairs more or less 

 poisonous. Branches spring from the buds at the axis or 

 angle of junction of stem and leaf. These angles are nodes, 

 the spaces between are internodes. Palms and some other 

 monocotyledons produce no lateral branches, having as a 

 rule only a crown of leaves at the top of the stem, with a 

 terminal leaf-bud in the centre. If this bud be destroyed, 

 the plant can grow no higher, and in some cases it 

 dies. The author, when visiting the South Sea Islands 

 in H.M.S. Challe?iger, in 1868, saw several instances of 

 wanton destruction of noble cocoa-nut palms fringing the 

 coral beach, which had been cut down by traders for the 

 sake of the tender leaf-buds or 'sailors cabbage. 5 The 

 aborigines of New South Wales and Queensland, and occa- 



