162 ELEMENTS OF BOTANY 
merely a prolongation of the filament. Within each lobe 
are two pollen-saes filled with mother cells from which 
the pollen grains are developed, each cell usually pro- 
ducing four pollen grains. 
After the anther has ma- 
tured, the two sacs of each 
lobe commonly run together 
into one eavity, which is only 
partially filled with pollen 
grains. The shape of the 
anther and the way in which 
it opens depend largely upon 
Fic. 119. Modes of discharging — the way in which the pollen 
Pollen, is to be discharged and how 
I, by longitudinal slits in the anther- it is carried from flower to 
cells (amaryHis); II, by uplifted 
valves (barberry); III, by a pore flower. The commonest 
at the top of each anther-lobe yethod is to have the anther- 
(nightshade). 
cells split lengthwise, as in 
Fig.119,I. A few anthers open by trap-doors like valves, 
as in IJ, and a larger number by little holes at the top, as 
in ITT. 
Sometimes the anthers face outward and open outward, 
as in the wild ginger (Fig. 98); but more frequently they 
face and open inward, as in the thistle, the pond lily, and 
the primrose (Figs. 109, 115, and 134). 
The pollen in inany plants with inconspicuous flowers, 
as the evergreen cone-bearing trees, the grasses, rushes, 
and sedges, is a fine, dry powder. Powdery pollen is 
adapted to be carried by the wind. In plants with showy 
flowers the pollen is often somewhat sticky or pasty. 
Sometimes pollen grains of this kind are bound together 
in small masses by fine, cobweb-like threads, as in the 
Milkweed Family (Asclepiadacea). 
