BOUGHS AND BRANCHES. 61 
their axils scales which are the true leaves, and carry flowers 
which are the exclusive characteristics of branches. 
In some plants the branches expand considerably, but in most 
others they remain slender; their terminal bud abortive, they 
become pointed and hardened at the extremities; in short, they 
are changed into spines as in the Hawthorn (Crategas oxycantha). 
A modification extremely curious and interesting in the form 
Fig. 75.—Subt i f Poiato, 
and consistence of branches occurs in the Potato (Solanum tuberosum), 
Fig. 75, which is developed under ground. The subterranean part 
of the stem is not green, and the leaves, if we can call them 80, 
