162 
merely a prolongation of the filament. 
ESSENTIALS OF BOTANY 
Within each lobe 
are two pollen-sacs filled with mother cells from which 
the pollen grains are developed, each cell usually pro- 
Fic. 119. Modes of discharging 
Pollen. 
I, by longitudinal slits in the anther- 
cells (amaryllis); II, by uplifted 
valves (barberry); III, by a pore 
at the top of each anther-lobe 
(nightshade). 
ducing four pollen grains: 
After the anther has ma- 
tured, the two sacs of each 
lobe commonly run together 
into one cavity, which is only 
partially filled with pollen 
grains. The shape of the 
anther and the way in which 
it opens depend largely upon 
the way in which the pollen 
is to be discharged and how 
it is carried from flower to 
flower. The commonest 
method is to have the anther- 
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 ITI. 
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 many plants with inconspicuous flowers, 
as the evergreen cone-bearing trees, the grasses, rushes, 
and sedges, is a fine, dry powder. 
adapted to be carried by the wind. 
Powdery pollen is 
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). 
