PHANEROGAMIA. 227 
productive organs are in one flower, when the ovaries are 
highest on the stem, the stamens being next, and the sterile 
leaves (if any) lowest of all (Fig. 127). There is, more- 
over, great diversity in the development of the sterile 
leaves, varying from a few small green or pale leaves to 
two or more distinct whorls of sepals (the outer) and petals 
(the inner) which may show great differences in size, shape, 
texture, and color. 
481, The stamens of Angiosperms often bear so little 
resemblance to leaves that their real nature would not be 
Fig. 128.—Pollen-cells with roughened walls. A, of Chicory; B, of Flowering 
Mallow (Lavatera). Highly magnified. 
suspected. There is usually a slender stalk, the filament, 
at the top of which are from one to four pollen-sacs, the 
latter forming the anther. We may regard the filament 
and its extension (the so-called connective) between the 
pollen-sacs as representing a very narrow leaf upon which. 
the pollen-sacs develop as outgrowths. Sometimes the 
stamen is broad, showing at once its leafy nature. 
482. The development of the pollen-cells is like that of 
the spores of Fernworts and the pollen of Gymnosperms. 
‘Certain internal cells (called pollen mother-cells) in the 
