AMERICAN 
JOURNAL OF BOTANY 
Vol. I October, 1914 No. 8 
STUDIES OF THE DEVELOPMENT OF THE PIPERACEAE 
II. The Structure and Seed-Development of Peperomia 
HISPIDULA 
(Continued from page 339 of this volume) 
Duncan S. Johnson 
D. The Carpel and Fruit; the Ovule and Seed 
The development of the ovary of this Peperomia is initiated by 
a swelling out of the base of the floral bract, due to the elongation of 
the subepidermal cells of the upper side of its stalk (figs. 24, 25, 26). 
This elevation, convex at first, later becomes flat, and then concave, 
as the rapidly growing margin pushes upward to form the wall of the 
single celled ovary (figs. 53, 54), Before this wall closes together to 
form the stigma, the floor of the ovarian cavity has begun to swell 
upward to form the single erect ovule, in the midst of which the pri- 
mary archesporial cell has now become evident (figs. 54, 55). The 
carpellary tube closes in to form the stylar canal at about the time the 
parietal cell is separated from the embryo-sac mother-cell (fig. 56). 
It is noteworthy that, from early in its development, the abaxial 
margin of the upgrowing carpel is longer than that next the axis (figs. 
55> 56). This longer side ultimately gives rise, at its tip, to the papil- 
lose, rounded, simple stigma (figs. 56, 57, 78). 
The wall of the carpel is at first only three or four cells in thickness 
(fig. 55). The portion about the ovule increases but little in thickness 
thereafter, and in the mature fruit is only 4 or 5 cells thick, except in 
one longitudinal strip along the abaxial side. There, in the mature 
fruit, it may become 6 or 7 cells in thickness (figs. 78, 100, loi, 108). 
In the stylar region, however, periclinal walls appear more abundantly^ 
especially on the abaxial side, and a section of the style may show it to 
be 16 or 18 cells in diameter (figs. 78, 79). Of the 4 to 7 layers of cells 
[The Journal for July (i: 303-356) was issued 8 Aug. 1914.] 
357 
