TRUE MATUliE OF ELOBAL ORGANS 



211 



really occurs is this: the flower-bud, as soon as it has 

 developed far enough to show the first rudiments of the 

 essential organs, contains them in the form of minute 

 knobs. These are developed from the tissues of the plant 

 in the same manner as are the knobs in a leaf-bud, which 

 afterwards become leaves (Fig. 87, II) ; but as growth 

 and development progress 

 in the flower-bud, its con- 

 tents soon show themselves 

 to be stamens and pistils (if 

 the flower is a perfect one). 



223. The Anther and its 

 Contents. — Some of the 

 shapes of the anthers may 

 be learned from Figs. 149 

 and 160.^ 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 cartied from flower to 

 flower. The commonest method is to have the anther- 

 cells split lengthwise, as in Fig. 160, I. A few anthers 

 open by trap-doors like valves, as in II, and a larger 

 number by little holes at the top, as in, III. 



The pollen in many plants with inconspicuous flowers, 

 as the evergreen cone-bearing trees, the grasses, rushes, 

 and sedges, is a fine, dry powder. In plants with showy 

 flowers it is often somewhat sticky or pasty. The forms 

 of pollen grains are extremely various. Fig. 161 will 

 serve to furnish examples of some of the shapes which 



Fig. 160.— Modes of discharging Pollen. 



I,l)y longitudinal slits in the anther-cells 

 (aiyparyllis); II, by uplifted valves (bar- 

 berry); III, by a pore at the top of each 

 anther-lobe (nightshade). 



1 See Kerner and Oliver's Natural History of Plants, Vol. II, pp. 86-95. 



