10 . BOTANY. 
expanded like a cake ; ¢esticulate, when there are two large tuberoid roots 
of nearly equal size. 
3. Ascending Axis, or the Stem. 
The stem is the part of the plant usually exposed above the ground, and 
bearing the leaves and flowers; it is produced by the successive development 
of leaf buds in a longitudinal and lateral direction. The stem bears different 
names, according to the character of the plant. Thus, in ordinary herbaceous 
plants, it is called caulis ; in the case of trees, truncus ; in shrubs, caudex ; - 
in grasses, culm ; in palms and ferns, stipe. When a distinct stem is present, 
the plant is called caulescent, when it is absent, acaulescent. True stems are 
sometimes absent in certain plants, which consist merely of expansions of 
cellular tissue, in the form of aggregations of cells. Such are called Thal- 
logens, or Thallophytes, and are represented by Chara, Conferva, and Alga. 
Stems, although more generally firm and erect, are sometimes weak, and 
either lie prostrate (procumbent stems), or climb like the ivy by means of 
suckers (scandent), or twist round other plants (volubile). The direction of 
the twist may be either from right to left, as mm Convolvulus, or from 
left to right, as in the Honeysuckle. Some plants exhibit both directions 
alternately. The twining plants have generally herbaceous stems; some, 
however, are woody, as the Clematis, Vine, Honeysuckle, &c., whose 
stems are called Sarmenta. Woody climbers are very common in 
tropical climates, where they are called Lianas. In some cases, the lateral 
extension exceeds the longitudinal, as in Testudinaria and some Cacti. 
There are certain points along the stems, at which leaf buds and branches 
appear; these are called nodes, and generally occur symmetrically. The 
spaces between the nodes are called internodes. A branch is but the 
development of a leaf bud from one of the nodes. WSpines are abortive 
branches, and, in many cases, by change of culture, may be developed into 
leaf or fruit bearing branches. 
Wlien the stem is woody and continues to increase indefinitely, we have 
either trees or shrubs ; trees when there is but one stem, shrubs when there 
are several stems, mostly of equal size, springing up together from the ground. 
A division of the shrub is sometimes made into the true shrub ( fruter), where 
there is a short stem; wnder shrub (suffruter), where this 1s hardly evident ; 
and low shrub (dumus), where the whole plant is low and spreading, the 
branches springing up together as a multitude of stems at or near the 
ground. The equivalent terms are arborescent, fruticose, suffruticose, and 
dumose. 
The transverse section of the stem, though generally circular, may be 
oval or even bounded by straight lines and angles. The various terms 
applied are, ferets ; half-terete ; compressed ; plano-compressed ; two-edged ; 
acute-angled ; obiuse-angled ; triangular ; quadrangular ; quinquangu- 
lar ; octangular ; multangular ; triquetrous, &c., whose significance is suffi- 
ciently evident, with the exception, perhaps, of the last, which refers to a stem 
with three concave faces. 
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