52 



The stamens are said to be : 



monaddphous, when their filaments are all united into - 



a tube ; 



diadelphous, when in two sets, or bundles ; 

 polyadelphous, when in several sets ; 

 syngenesious, when the anthers are united in a ring ; 

 didynamous, when there are 4 stamen s ; two of them 



long and two of them short ; 

 tetradynamous, when there are 6 stamens, 4 of them 



long and two of them short. 



If the stamens are inserted on the petals they are cpi- 

 peialous, and if opposite the petals they are antipetalous. 



If the stamens are the same number as the sepals and 

 petals, the flower is isostemonous, if the stamens are double the 

 number, the flower is diplostemonous, and if they are double 

 the number and they do not alternate correctly with the 

 petals, the flower is obdiplostemonous. 



Stamens which protrude beyond the corolla are said to be* 

 exserted ; if hidden by the corolla they are included. 



The anther is said to be : 



introrse, when the thecse are turned inwards towards the 

 centre of the flower, i.e. when the thecaB are on 

 that side of the anther which faces the floral axis 

 (ventral side) ; 



', . extrorse, when the theca3 are turned outwards, facing 

 away from the floral axis, i.e. when the thecse 

 are on that side of the anther which is turned 

 away from the axis (dorsal side) ; 



innate, when the filament appears to be fixed in the 

 centre of the base of the anther, the thecaa not 

 facing inwards or outwards. The anther is also 

 sometimes said to be basi fixed in this case ; 



adnate, when the filament appears to run up at the back, 

 or front, of the anther, the thecae facing inward s,. 

 or outwards ; 



versatile, when it swings freely at the end of the filament ; 



dorsifzed, when the filament appears to be inserted in 

 the back of the anther ; 



The stamens sometimes branch, e.g. in the Castor Oil Plant. 

 This is often indicated by the anthers being only one-celled, 

 i e. each is really half a stamen, although in some cases this may 

 be due to the non-development of half the stamen Anther:? 



