170 Our Field and Forest Trees 



pear trees growing on abandoned farms often 

 bear thorns, and also short, spiky branches, as 

 sharp and stiff as knitting needles, which bear a 

 starveling leaf or two. 



These thorns and prongs protect the trees 

 while they remain neglected, but when the or- 

 chard is cared for, and the ground enriched, they 

 " are apt to be re-converted," says Darwin, 

 " into branches." Some trees, like the honey 

 locust, always bear thorns, whether they grow in 

 rich or in barren soil. 



Their woody thorns prove themselves akin to 

 branches, because they appear just where sprays 

 might be found. 



Those of the haws come from buds formed, 

 after the habit of leaf-buds, in the place where 

 last year's leaves grew. 



Those of the thorny locust grow beside the 

 scars left by falling autumn leaves, or they appear 

 on the trunk in bristling tufts corresponding to the 

 tufts of leafy sprays on the trunks of willows and 

 elms (Fig. 42). 



And as leaf-buds can grow out Into thorns when 

 the tree is rooted in poor soil and living a hard 

 life, the thorns which put forth one or two stunted 

 leaves remind us that under happier conditions 

 they might have been branches. 



Uncared-for trees, living in poor soil, approach 

 the condition of desert shrubs, which are almost 

 always thorny. Fig. 43 represents an apple tree 



