STUDIES OF THE DEVELOPMENT OF PEPEROMIA HISPIDULA 33 1 
It is evident from a comparison of this Peperomia with the several 
types in the series of BraziHan species studied by Jaderholm, that 
P. hispidula is a species diverging farthest from the vegetative structure 
most characteristic of the genus as a whole. The gross and minute 
structure of the root, stem and leaf of P. hispidula are far simpler than 
those of most species, and are even somewhat simpler than in P. delica- 
tula and P. tenera, the simplest types thus far described (Jaderholm, 
1898). It seems altogether possible that the highly peculiar type of 
embryo-sac development found in P. hispidula is to be attributed in 
some way to the same environmental conditions in its habitat that 
seem to have modified its vegetative structure so profoundly. 
B. The Development of Spike and Flower 
The flowers of Peperomia hispidula are arranged in terminal spikes, 
which may occur in series, one spike opposite each of the four or five 
terminal leaves of the shoot (figs, i, 22, 23). The spike consists of 
from 6 to 14 flowers (commonly there are 9 or 10). When the spike 
is mature it may, with its stalk, have a length of 15 millimeters (fig. 
22). The axis of the mature spike is about half a millimeter in diam- 
eter, and the flowers are widely scattered along it. The vascular 
system of the spike is of a single central bundle, similar to that of 
the stem (figs. 23, 35). The vascular bundle of each flower runs down 
through one internode below the insertion of the bract before joining 
that of the axis (fig. 56). 
Each flower consists of a single ovary and two rather long-stalked 
stamens, all borne in the axil of a short-stalked bract with an orbicular 
end about half a millimeter in diameter (figs. 22, 25) . The lowest bract 
of the spike generally bears the usual carpel and two stamens above 
it, but at the tip of the spike are found from one to four or five bract- 
like outgrowths of the axis, which are entirely without rudiments of 
either pistil or stamens (fig. 22). Only in rare cases were unisexual 
flowers found, and these were always pistillate only. The distribution 
of sexes is therefore much more definite and constant here than in 
Piper Betel (Johnson, 1910, p. 716). The pistils and stamens initiated, 
however, often fail to produce mature embryo sacs and microspores 
and usually only 4 or 5 ripe seeds are found on a single spike. 
The development of the bract is initiated by the formation of a 
rounded lateral projection from just below the growing point of the 
axis (fig. 24). This protuberance soon begins to flatten at the end; 
