63 



PRACTICAL BOTANY. 



trorse (turned inward), when it faces the pistils, as in 

 Magnolia (Fig. d). 



The VEESATILE ANTHEE is usuallj introTse (turned to- • 

 ward the axis of the flower) — rarely extrorse. 



The CONNECTIVE is often inconspicuous, or even want- 

 ing, so that the anther-lohes are "in close contact. Some- 

 times it outruns the anther and tips it with an appendage, 

 as in Magnolia, Ziriodendron, Violet, Asaricm, etc. 



113. At maturity, the anther-cells open, or become 

 dehiscent, to discharge the pollen. There are three modes 

 of dehiscence — namely, a, the valvular — that is, the split- 

 ting open by two lateral, longitudinal lines, one on each 

 lobe of the anther (Figs, y, g) ; h, the porous, in which the 

 cells open by a pore or chink at the apex of the lobe (as 

 in Pyrola, Fig. K), and each lobe ia sometimes prolonged 

 into a tube, as in Yaccinium,' c, the opercular, in which 

 each cell opens by a lid, which, as though attached to the 

 apex by a hinge, turns upward like a trap-door, fis in 

 JBerieris (Fig. i). The commonest mode of dehiscence is 

 the valvular. 



Cut XI. 



114. The POLLEN, when examined under the micro- 

 scope, is found to c6nsist of grains, generally globular or 

 ovoid, sometimes triangular or polyhedral, etc., but all 

 alike in the same species. Each pollen-grain is a mem- 



