COMPOUND ORGANS OP PLANTS. 



delphous stamens (^uoVoj one, and d5f^6j brotherhood;) diadel- 

 phous, when the filaments are united into two bundles, as in 

 the pea and fumitory. In the latter instance, the same number 

 of filaments cohere together in the two bundles, each of them 

 being composed of three stamens, but in nearly all papiliona- 

 ceous flowers, out of ten stamens nine are united by their 

 filaments while one is free. When the filaments cohere into 

 three bundles, the stamens are triadelphous, as in the St. 

 John's-wort, (Hypericum,) Fig. 47; and when they grow 

 together into many bundles, polyadelphous, as in Ricinus com- 

 munis, the Castor oil plant, Fig. 48. 



Fig. 47. Fig. 48. 



Fig. 47. Vertical section of St. John's-wort (Hypericum.) This flower has tria- 

 delphous stamens, and a tricarpellary pistil. Only two of the hundles of stamens 

 are visible, the third having been removed along with a part of the pistil. 



Sometimes the stamens adhere to each other by their anthers, 

 the filaments being free, they are then said to be syngenesious or 

 synantherous (avv together, and ysvs ois origin, or cw/^pa anthers). 

 This kind of union occurs in Composite flowers, of which the 

 cichory-is a sample, (Fig. 49.) Occasionally, however, the 

 union of the stamens takes place through their entire length, 

 their filaments as well as their anthers cohering, as in Lobelia, 

 (Fig. 50.) At length the androecium, instead of forming a dis- 

 tinct verticil about the pistil occupying the centre of the flower, 



