FILAMENT. 



75 



be epigynous, or from under the pistil, their true origin, and 

 called hypogynous. (Fig. 121.) 



Fig. 122. 



Fig. 124. 



Monadelphous 

 stamens. 



Diadelphous stamens. 



Polydelphous st amena. 



120. Stamens are often united by their filaments, forming a 

 tube, as in the Malva, when they are said to be monadelphous 

 (Fig. 122), or in one brotherhood. In other cases they are united 

 into two sets, when they are said to be diadelphous (Fig. 123), 

 as in the Pea : if into several sets, the term polydelphous is ap- 

 plied (Fig. 124), as in some Hyperica. 



If the stamens project beyond the corolla, they are said to be 

 exserted, and included when shorter than the corolla. 



When the stamens all turn to one side of the corolla, they 

 are said to be declinate. When a flower has four stamens, two 

 of which are longer than the other two, they are didynamous 

 (Fig. 125). If there are six, with four the longest, then they 

 are tetrad ynamous. (Fig. 126.) 



Fig. 125. 



121 . The filament is generally, as its 

 name implies, a slender thread-like or- 

 gan, having a bundle of vessels in its 

 center composed of woody fiber and 

 spiral vessels, and corresponds undoubt- 

 edly to the petiole of the leaf. It as- 

 sumes a variety of forms. Its normal 

 form is found in the Rose, Apple, and 

 Lily. In the Canna the filament re- 

 sembles so much a petal that it would 



Fig. 126. 



Didynamous 

 stamens. 



Stamens 

 tetradjnamous. 



Epigynous \ Hypogynous 1 — 120. When monadelphous? Polydelphous? 

 When are stamens exserted • When included \ Declinate ? Didynamous ? 

 Tetradynaraous'— 121. What is the filament? What does it resemble in 

 the Cauna? 



