THE ANGIOSPERMAE 



"73 



united, through intermediate stages in which one stamen only is isolated, 



the other four being more or less united in pairs. The completest union is 



shown by Cyclanthera (Fig. 1141), the male flowers of which display a 



central structure, shaped rather 



like a collar stud and called a syn- 



andrium, in which all five stamens 



are completely coalescent even to 



the pollen locuH, of which there 



are two, one above the other, 



running horizontally around the 



circular cap of the synandrium. 



The flowers of Cucurbitaceae 

 are unisexual and it is noteworthy 

 that synstemony is more generally 

 shown by the male flowers of dicli- 

 nous plants than by hermaphrodite Fig. 1143.— Synstemonv in: A, Pandanus. B, 

 flowers. Examples of the former Myristka. {After Le Maout and Decaisne.) 



are: Begonia, Schizandra, Myristica (Fig. 1143), Nepenthes, Clusia (Fig. 

 1 141), Pandanus (Fig. 1 143) and Typha. It will be observed that the major- 

 ity of these are Dicotyledons and the phenomenon is in fact much com- 

 moner in this group than among Monocotyledons, which, indeed, are more 

 rarely diclinous. 



Staminal concrescence in hermaphrodite flowers is well exemplified by 

 the Malvaceae, in w^hich the filaments of the numerous stamens are united 

 into a tube around the gynoecium. One member of the family, the fre- 

 quently cultivated shrub Plagianthus (Fig. 1144), carries matters even 

 further, for the petals, which are smaller than the sepals, are also concres- 



FiG. 1 144. — Synstemony in Plagianthus. A, 

 Flower. B, Androecium with adherent 

 petals. (After Le Maout and Decaisne.) 



cent with the staminal tube, from which they appear to arise. The develop- 

 ment of a staminal tube reaches its height in the Meliaceae, where it over- 

 tops the perianth and is the most conspicuous object in the flower. It is 



