118 



THE STAMENS. 



Fig. 223. Fig. 224. 



Fig. 223. Dydynamous stamens. 

 Fig. 224. Tetradynamous sta- 

 mens. 



it is not unusual to find one-half of the stamens shorter than the other. The essential 

 differences in size are such as are permanent in the 

 same species ; and of these there are two examples. 

 Many flowers with a bilabiate corolla, as the Foxglove 

 and Mint, have two long and two short stamens; 

 whence they are called Didynamous (Fig. 2 2 3). The 

 cruciate corolla, as in the Turnip and Radish, 

 has usually four long and two short stamens; and 

 to them the term Tetradynamous (Fig. 224) is aptly 

 applied. 



The number and arrangement of the stamens was a 

 chief element in the classification of Plants by Lin- 

 naeus ; and of the twenty-four classes arranged by 

 him we- have now referred to five. Eleven others 

 vary simply according to the number of stamens, 

 from one upwards, and are named from Greek words having that signification. Thus 

 Monandria signifies one stamen ; 

 Diandria, two stamens ; and so on to 

 Dodecandria, which represents twelve 

 or more stamens up to twenty. 



Two others viz. Icosandria and 

 Polyandria have an indefinite number 

 of stamens, which in the former are 

 perigynous, and in the latter hypogy- 

 nous (Fig. 225). Thus no fewer than 

 eighteen out of twenty-four classes 

 are arranged according to the number, 

 length, and place of insertion of the 

 stamens. 



"We have hitherto regarded the 

 stamen as a whole, but it is naturally 

 divisible into three parts, each of 



which has special functions and analogies. These are the filament, anther, and its 



contained pollen, the first of which may be 

 entirely absent. 



The filament is, as its name implies, a 

 thread-like organ, attached by its base to the 

 peduncle, and by its apex to the anther, and 

 a, lily ; is simply a pillar on which to rest the 

 ;oe; d, be; erry; , latter> and a conduit through which vessels 

 and fluids pass for the nourishment and 

 growth of the pollen and its case the anther. It is the analogue of the petiole 

 of the leaf, and like it consists of a bundle of vascular tissue, enveloped in cells, 

 and a delicate cuticle. Its figure is seldom quite cylindrical, but more com- 

 monly tapers towards the top, when it is said to be awl-sbaped. In a few in- 

 stances, as in the Meadow Rue, it is the thickest at the top; in others it is spiral, or is 

 bent like an elbow or knee (geniculate), or bifurcates into two branches. In some 

 instances it assumes a foliaceous form, and likewise in most sterile stamens. The 



Fig. 225. The Poiyandrous flower of the Poppy. 



Fig. 226. Different forms of stamens. 

 b, cluck weed ; c 

 ginger ; /, sage. 



