SHRUBS AND TREES 
*55 
them are of sympodial growth. In tropical regions most 
trees are evei'green. Two chief types occur, those w r ith 
branched stems and those with columnar usually unbranched 
stems. The former branch in the ordinary way, but their 
branches very often grow almost erect and parallel, instead 
of spreading out in all directions, and the leaves are borne 
in rosettes, or tufts at the ends of the twigs. The latter are 
best illustrated by the Palms, many Araliaceae, Cycads, &c., 
with an erect trunk bearing a rosette of large leaves. Both 
forms are excellently suited to growth in forests, their leaves 
thus being all exposed to light at the top of the tree. In 
the dry climates of the sub-tropical regions, many deciduous 
trees and shrubs are found, the leaves falling at the beginning 
of the dry period. 
The woody plants of temperate climates form winter- 
buds (often even when evergreen, as seen in Rhododendron, 
&c.) at the ends of their branches in autumn ; these contain 
all or part of the next year’s growth in a more or less 
developed condition. The bud is exposed to evaporation, 
cold, wet, and other dangers, but is protected in most cases 
by scales ; these are sometimes modified leaves, as in Acer, 
Aesculus, &c., sometimes the stipules of the outer leaves, 
as in Magnolia, Bucklandia, &c. ; in some cases the scales 
are hairy, in others glandular or resinous, so that they 
form an efficient protection. In Juglandaceae, Viburnum, 
Sophora, &c. the winter-buds are not protected by scales, 
but their leaves themselves are more or less hairy or other- 
wise protected. Many winter-buds are able to absorb 
water from rain, and this helps them to recover their losses 
by evaporation at a period when the roots are not active. 
In spring the winter-buds elongate, casting off their 
scales ; the large buds of horse-chestnuts, pines, and other 
plants grow rapidly to their full elongation and then 
stop, so that the growth is definite , while in Rosa, Salix, 
Gleditschia and many other plants the growth continues 
till checked by the cold (i.e. is indefinite ), the terminal part 
of the shoot dying and the new growth in spring starting 
from a lateral bud. In lilac (Syringa) and other plants the 
terminal bud regularly aborts and growth starts from the 
laterals in the succeeding year. The lateral buds in Robinia, 
Platanus, &c. are protected in summer by the bases of the 
