PHARMACEUTICAL BOTANY 
150 
pollen or microspore cells. Filling the cavities of the four sporangia 
are the mature pollen grains. The connective shows in or near its 
center a vascular bundle with xylem uppermost and phloem down- 
ward, surrounded by thin- walled cellular tissue, from which the indu- 
sial and sporangial substance has matured by extension. 
Anther Dehiscence. — This is the breaking open of the anther to 
discharge the pollen. 
When fully ripe the dividing partition between each pair of spor- 
angia usually becomes thinned, flattened and ultimately breaks down, 
Fig. 66. — Cross-section of a mature lily anther. The pairs of pollen chambers 
unite to form two pollen sacs, filled with pollen grains; s, modified epidermal cells 
at line of splitting. ( From a Text-book of Botany by Coulter, Barnes, and Cowles. 
Copyright by the American Book Company, Publishers.) 
while the elastic and resistant endothecium, steadily pushing against 
the more delicate and now shrinking exothecium causes rupture 
where endothecium is absent, namely along opposite lines of the 
anther wall. Thus arises a line of anther dehiscence called longi- 
tudinal anther dehiscence on either side of the anther sacs. In the 
division Solanece of the family Solanaceee which includes Belladonna, 
in some of the Ericacece as Rhododendron and Azalea, etc., the 
anthers dehisce by small apical pores from which the pollen is shed. 
This kind of dehiscence is called apical porous dehiscence. Again, 
in Lauracece and Berberidacece , the anthers dehisce by recurved valves. 
This is called valvular dehiscence. 
