24 



DOMESTIC BOTANY. 



The first or main branches are called limbs, the 

 smaller branchlets (ramules), and the ultimate twigs 

 (ramlets). In the araucaria and arbor- vitse section of the 

 fir family, the branches consist of numerous ramlets 

 formed of small, firm, close, imbricated scales, which 

 are, with the ramlet, permanent for several years, the 

 latter ultimately falling away entire. To all such leaf- 

 growths the term thyclads is applied. In the celery- 

 topped pine of Tasmania {Phyllocladus) , and its congener 

 of New Zealand, the ramlets are flat and broad, assuming 

 the character of leaves, there being no true leaves. 



The stems and branches of many plants are furnished 

 with what may be called weapons of defence, chiefly 

 consisting of prickles and thorns, which are either pro- 

 duced on the bark, or connected with the wood ; the 

 first are called aculei, and the latter spines; but these 

 terms are indifi'erently applied to prickly and thorny- 

 plants in general. They are common to many of the 

 apple, pea, rose, orange, gooseberry, and cactus families, 

 and are either simple and straight as in the gooseberry 

 and hawthorn, curved or hooked as in roses and some 

 palms, forked as in the Natal plum, algarobs, and others 

 of the mimosa family, or branched, as in the honey locust 

 tree of North America, in which they are at least six inches 

 in length, growing in clusters on the stem and main 

 branches, and presenting the appearance of chevaux- 

 de-frise. In the cactus family they vary from hair-like 

 bristles to spikes six or more inches in length, some 

 being flat like swords, others like broad hooks, and of a 

 hard bony nature. In the curious Mexican shrub 

 Fouquiera, the midrib of the leaves is permanent, and 

 becomes a hard stifi" spine. 



Nettles, loasads, and jatropha are furnished with 



