44 
THE STEM 
undertaken by the stem in perennial plants. In woody 
plants the materials for subsequent growth are usually stored 
in the wood of the stem, and only rarely does storage take 
place to such an extent as to necessitate extra growth in 
thickness beyond that necessary for the performance of the 
functions already dealt with. Cases are found in Bombaca- 
ceae, Jatropha sp., &c. Herbaceous stems above ground 
are not usually suited to storage purposes, though some 
cases occur (succulent Xerophytes, see Chap. III.), as they 
die down in winter (or the dry season in warm countries) 
and here storage is usually found below ground, in such 
peculiar shoots as bulbs, corms, rhizomes, tubers, &c. (see 
Chap. III., Herbs, Xerophytes, &c.). Such shoots also 
lend themselves readily to vegetative reproduction. 
Other types of stem are found in water-plants, climbing 
plants, xerophytes, epiphytes, &c. (see Chap. III.). These 
illustrate the modification of structure bound up with the 
modification of certain functions due to varying climate 
or situation. 
Like roots, shoots are often adventitious (or secondary if 
there are also primaries), arising by the budding out of 
growing points on roots (e.g. Podostemaceae, Ailanthus, 
Anthurium sp., and many trees), or on stems (many tropical 
trees, Testudinaria, &c.). Account must always be taken of 
such cases in dealing with homology of shoots. 
The habit of the stem, i.e. its general external appearance 
and impression, will be dealt with in Chap. III. A number 
of descriptive terms, however, may conveniently be put 
together here. 
Most of these explain themselves or are explained above and in 
Chap. III. Stem and leaf should always be described together for the 
sake of accuracy and conciseness. 
Stems may be annual , biennial , or perennial ; erect , climbing, 
twining , prostrate or procumbent , creeping , ascending or decu?nbent 
(bending upwards from a prostrate base), gloating, &c. ; they may be 
unbranched ( simple ) or branched (describe mode of branching) ; if 
branched they may be caespitose (a tuft of shoots from the base, as in 
many grasses), fastigiate (many branches parallel to the stem, as in 
Lombardy poplar), or with fascicles (tufts) of lateral branches. The 
stem or branches may be a corm , bulb, tuber, rhizome , runner, stolon , 
sucker, offset , phylloclade , tendril, &c. Adnation may occur, or long 
and short shoots ; the stem may be a monopodium or a sympodium ; it 
may be ‘ condensed ’ bearing ‘ radical ’ leaves, and run out into a scape 
