1921} JURICA—DIPSACUS I4I 
(fig. 2). Probably the presence of an additional pair of clasping 
leaves per lateral branch is responsible for the total absence of 
secondary branching, especially since all the specimens examined 
showed this regularity. For the sake of certainty in this regard, 
however, a more extensive field study is necessary. Another 
noteworthy feature in regard to the development of new branches 
is the inequality of a developing pair. At times this inequality is 
so marked that a given shoot or branch happens to be three or 
even five times as long as its immediate neighbor, arising from the 
axil of the leaf directly opposite. This undoubtedly is due to the 
fact that the development of both members of a pair of lateral 
branches is not simultaneous. 
Floral head 
The type of inflorescence of D. sylvestris is a head or capitulum, 
surrounded by an involucre of long upcurving spiny bracts 
arranged in cycles of five, with the members of the outer cycle 
extending beyond the head, which they encircle. The bracts 
forming the succeeding inner cycles gradually become shorter, so 
much so that the members comprising the fifth inner cycle are 
almost equivalent in length to that of the bracts subtending the 
individual flowers of the head. 
In its development the floral head is intimately associated with 
the origin of lateral or secondary branches, for the central or main 
stem, as well as every individual branch, is terminated by this 
type of inflorescence. The minute protuberance arising from the 
axil of a clasping leaf, and destined to develop into a new branch, 
is in reality a capitulum initial. Insignificant though it is at first, 
it immediately begins to round out, and the bracts which enter into 
the composition of the involucre are prompt in making their 
appearance (fig. 4). Almost concomitant, or at least following in 
close succession, are the clasping leaves of the new shoot, which 
appear as lateral outgrowths or papillae just below the origin of 
the bracts (fig. 5). As soon as the initials of these members are 
differentiated, the entire new shoot becomes one mass of growth. 
Not only does a rapid elongation of the region, both directly above 
and below the origin of the leaf initials, set in, but this elongation 
