CHAPTER X. — THE STAMENS, OR ANDRCECIUM. 77 



when in three sets, as in some Hypericums, triadelphous, etc.; 

 and when in a considerable number of sets, as in the Orange, 

 Fig. 233, they are called polyadelphous. When stamens are united 

 by their anthers, as they are in the Sunflower, Dandelion (Fig. 

 234), and other Composite, they are called syngenesious. 



In some flowers, as in many Mints and Figworts, there are 

 four stamens, two of them longer than the other two ; such 

 stamens are said to be didynanwus. In the Mustard and other 

 members of the Cress family, there are four long and two 

 short ones ; the stamens of such flowers are said to be tetra- 

 dynamous. 



Occasionally the filament is wanting, and the anther is then 

 described as sessile. Sometimes, however, the anther is wanting, 

 or no longer functional ; such a stamen is described as sterile or 

 abortive. 



The Filament. This probably corresponds, in most cases 

 at least, to the petiole of the leaf, while the anther is regarded 

 as homologous with the blade. It assumes a great variety of 

 forms in different flowers. Sometimes it is capillary, or very 

 slender and hair-like, as in some grasses ; sometimes it is fili- 

 form, or thread-like, as in many of the Rosaces ; sometimes it 

 is petaloideous, or petal-like, as in some of the stamens of the 

 White Water-lily ; sometimes it is toothed, as in some species of 

 Onion ; sometimes it is appendaged, as in the Milk-weed ; most 

 commonly it is simple, as in the Geranium, but sometimes it is 

 branched, as in the Castor-oil Plant. Its different forms com- 

 monly bear some relation, more or less evident, to the mode of 

 pollination. 



The Anther. The anther is usually two-lobed and two- 

 celled, that is, contains two pollen-sacs, but occasionally we 

 find it twice as many lobed and celled, and, on the other hand, 

 we sometimes find stamens where, as in those of the Hollyhock, 

 the two normal pollen-sacs have become confluent into one. 



There are different ways in which the anther may be inserted 

 on its filament. When it stands erect on the end of the filament, 

 as in Fig. 235, it is described as innate ; when the two lobes of 

 the anther appear to grow fast to the side of the filament, or the 

 latter appears to be produced through the middle of the anther, 

 as in Fig. 236, it is called adnate ; and when the anther swings 



