STAMENS. '677 



To the petals the beautifully-varied colours of plants are due, and 

 though it is not possible to enter upon the subject here, we may conclude 



that the various beauties of the 

 colours of flowers are owing to light 

 and air acting upon the various 

 " colouring matters " contained in 

 the plant. Seeds planted in a dark 

 cellar will spring up pale ; admit 

 light, and they will become green, 

 for light thus acts upon the chloro- 

 phyl. But the flowers of the plant 

 are not so dependent upon light, Fig. 775. 



Fig. 774. Labiate corolla. MI j -n/r late. 



as can easily be proved. Many 

 interesting experiments have been made upon flowers by acids and gases.* 



The STAMENS are the next in order for our consideration. They are 

 found within the petals (or the calyx if no petals be present). Stamens vary 

 very much in different plants both in number and general features but, as 

 in the case of petals, they keep, as a rule, to certain numbers and doubles of 

 them. The stamen consists of two portions a lower, thread-like part called 

 the filament, and an oblong bag or head, termed the antlier. This contains 

 a powdery matter called pollen, and is the essential part of the stamen. The 

 filament, which corresponds to the petiole of the leaf, may be absent, in which 

 case the anther is called sessile. A lily will show the stamens perfectly, the 

 anther being prominent in many other plants also, such as daffodils and 

 fuchsias. 



The stamens are very important organs with regard to the classification 

 of plants for number, length, and position, whether free or united, are all 

 characteristic features. The length of filaments is always the same in the 

 same kind of plant, and therefore is a very palpable test. 



The anther contains the pollen, a powdery matter, usually yellow-coloured, 

 tmt sometimes also red, brown, violet, or green-coloured. Pollen-grains 

 vary from -^ to -g-Ju of a line in diameter. Under a powerful microscope 

 they appear as ellipsoidal, or sometimes spherical, triangular, polyhedral 

 vesicles, filled with a granular semi-fluid matter. To effect fecundation, 

 the pollen-grains must come into contact with a certain part of the plant 

 which is intended to receive them, and which is called the ovule, and is found 

 in the fourth or innermost verticil of the flower, the pistil. Of the further 

 development of the ovule, we shall have occasion to speak in the paragraph 

 treating of the seed. 



At the proper time the anther opens and discharges its contents, the 

 pollen-grains, some of which reach the place of their destination. The 

 position of the stamens to the pistil is usually such that the latter can readily 



* Respecting artificial colouring of flowers, see page 329. 



