1921] JURICA—DIPSACUS 139 
leaves is deep green, while the veins and midribs are nearly white 
and beset with spines. A stout taproot, often more than a foot 
long and with many branching rootlets, serves to anchor the plant. 
During the second season the flat rosette sends out a shoot, which 
develops into a stout, erect, and strongly ridged stem, beset with 
sharp spines (3), which often grows to a height of 3-6 ft., the degree 
of branching depending upon the richness of the soil. If viewed 
in cross-section, the stem is rather tough and woody, characterized 
by a large pith, which gradually breaks down, so that the older 
portions of the stem are hollow. No attempt has been made to 
include a study of the anatomical features. The stem leaves 
occur in pairs, opposite each other, with their bases so closely 
clasping the stem that often they are united at the base, and thus 
form cups which retain water (3). The clasping leaves do not 
make their appearance on the stem in the same plane, but observe 
some degree of regular alternation. Thus, if one pair of leaves is 
pointing north and south, the alternating pairs (the next pairs 
immediately above and below) point east and west (2). 
According to VELENOvSsKY (8), the axils of leaves as a rule 
contain an active meristem, which may give rise to new branches 
or axillary shoots. This is precisely what takes place in D. sylvestris, 
although with some modification. New branches or shoots do not 
develop from the axils of all clasping leaves, for some abortion 
takes place, especially in the case of plants growing in poor rocky 
soil. In.such an environment the plants of this species are branched 
very little, and in some cases not at all. Whenever new shoots or 
branches are given off, however, they always occur in the axils of the 
clasping leaves. If two or more succeeding pairs of clasping leaves 
give rise to lateral branches, as is often the case with D. sylvestris 
found growing in a slightly better soil, the shoots make their appear- 
ance at right angles to the ones above and below. While the lateral 
branches are still small and scarcely noticeable, except upon closer 
examination, in turn they also give rise to new daughter shoots 
from the axils of their clasping leaves, which follow the same 
general plan of development as those arising from the main or 
central stem. Plants with secondary branches are common, 
whereas plants with tertiary or quarternary branching are less 
