112 COMPOUND ORGANS OF PLANTS. 



are usually colored green, and are the nearest allied to the 

 leaves of the stem, both in form and appearance ; the petals of 

 the corolla, or innermost floral envelope, are usually of some 

 other color than green, as for instance, white, red, blue, yellow, 

 or some intermediate shade of these colors, and more delicate 

 and beautiful in their texture than the sepals. The stamens 

 marked c in fig. 16, are situated immediately within the corolla, 

 and surround the pistils marked d, or central organs of the 

 flower. The stamens are collectively termed the androecium 

 (o*);p a male, and oixiov habitation), and are considered to be 

 the male organs of the plant. The pistils occupy the centre 

 of the flower, are surrounded by the stamens and floral 

 envelopes, and after flowering are changed into fruit, and con- 

 tain the seed. The pistils are collectively termed the gymnoe- 

 cium (yvvii a female, and iixiov a habitation), and are considered 

 to be the female organs of the plant. 



All these organs of the flower are situated on the summit 

 of the peduncle or flower-stalk, and the part on which they 

 are situated has received the name of thalamus, torus, or 

 receptacle. 



The diiferent organs of the flower are verticillate leaves 

 brought into close proximity, in consequence of the non-devel- 

 opment of the floral intcrnodes. This fact is beautifully con- 

 firmed by the appearance of an internode, or naked portion of 

 stem, in some species between one or more of the floral whorls, 

 by which they become separated from each other, just as the 

 whorls of leaves are separated on the stem. Thus the inter- 

 node, or naked interval of stem between the stamens and pistils 

 is developed in Euphorbia corollata, flowering spurge (Fig. 

 17), the pistil a being elevated, after, it is fertilized, on a little 

 stalk, and thus lifted, as it were, from out of the midst of the 



