SECTION 9.] 



POLLEN. 



103 



line along the whole 



293. By suppression in certain cases the anther may be reduced to one 

 cell or halved, hi Globe Amaranth (Fig. -2^3) there is a Bingle cell without 

 vestige of any other. Different species of Sage and of the While Sag 

 California show various grades of abortion of one of the auther-cells, along 

 with a singular lengthening of the connective i Fig. 302-305 . 



294. The splitting open of an anther for the discharge of its pollen is 

 termed its Dehiscence. 



295. As the figures show, this is commonly by 

 length of each cell, either lateral or, 

 when the anthers are extroise, often 

 along the outer face, and when introrse, 

 along the inner face of each cell. Some- 

 times the opening is only by a chink, hole, 

 or pore at the top, as in the Azalea, Py- 

 rola (Fig. 307), etc. ; sometimes a part of 

 the face separates as a sort of trap-door 

 (or valve), hinged at the top, and open- 

 ing to allow the escape of the pollen, 

 as in the Sassafras, Spice-bush, and Barberry (Fig. 308). 



296. Pollen. This is the powdery matter, commonly of a yellow color, 

 which tills the cells of the anther, and is discharged during blossoming, 



O • 



309 310 311 



after which the stamens generally fall or wither away 



812 



313 

 Under the micro- 

 scope it is found to consist of grains, usually round or oval, and all alike 

 in the same species, but very different in different plants. So that the 



<*P 



314 816 316 817 



plant may sometimes be recognized from the pollen alone. 

 are shown in the accompanying figures. 



818 

 Several forms 



Fig. 306. Stamen with tin- usual dehiscence <>r auther down the side of each cell. 



Fig. 307. Stamen of Pyrola; cells opening by a terminal hole. 



Fio. 308. Stamen of Barberry; cells of anther each opening by an uplifted valve. 



Fig. 309. Magnified pollen of a Lily, smooth and oval; 310, of Echino<v<tis. 

 grooved lengthwise; 311, of Sicyos, with bristly points and smooth bands; 812, oi 

 Musk Planl (Miniulus), with spiral gro twelve-sided and 



dotted. 



Fio. 314. Magnified pollen of Hibiscus and other Mallow-plants, beset with 

 prickly projections ; 315, of Circaca, with angles bearing little lobes; 816, ol 



