142 COMPOUND ORGANS OF PLANTS. 



necessarily sterile ; but if some of th€ stamens are perfect, 

 even in a double flower, there may be fruit. 



Tlie number of stamens which compose the androecium 

 varies very considerably. There may be only one, as in Calli- 

 triche verna, Water star grass, or many hundreds as in the 

 poppy. The flower, according to the number of its stamens 

 from one to ten, is said to be monandrous (juwoj one, w^p male,) 

 diandrous (Stj two,) triandrous (fpftj three,) tetrandrous (fcrpaj 

 four,) pentandrous {jtivtc five,) hexandrous (J'i six,) heptan- 

 drous (Ijtra seven,) oetandrous [ixtu eight,) enneandrous Qwii 

 nine,) decandrous (iixa ten.) Above ten there is no regularity 

 in the number of the stamens. All flowers having from twelve 

 to twenty stamens, are designated as dodecandrous (&u&cxa 

 twelve;) and if their number exceeds twenty, Polyandrous 

 [itotMi many.) 



Propm'tion of the stamens. — The relative length of the 

 stamens is not always the same, the filaments being sometimes 

 more or less developed in the same flower. In some cases 

 there exists a definite relation as regards number between the 

 long and the short stamens. When a flower encloses four 

 stamens of which two are constantly the longest, it is called a 

 didynamous flower, (Sis twice, and tvvafui power;) Fig. 44 ; 

 and when there are six stamens in the same flower and four of 

 them longer than the other two, the flower is said to be tetra- 

 dynamous, (T'^fpa; four, and Sirajuts power ;) Fig. 45. The 

 natural orders Labiatse and Scrophulariaceje furnish us with 

 samples of the first, and Cruciferse of the last disposition of 

 the stamens. In the wood sorrel, (Oxalis,) there are ten 

 stamens, monadelphous at their base, five long and five short, 

 which alternate with each other. 



Connexion of tlie stamens. — The stamens, in common with 



