24 STRUCTURAL BOTANY. [19, 20. 



52. Corolla is a Latin word signifying a little 

 crown, applied to the interior envelope of the flower. 

 It consists of one or more circles of leaves, either dis- 

 tinct or united by their edges, usually of some other 

 color than green, and of a more delicate texture than 

 the calyx. Its leaves are called petals. 



53. Perianth (nept, around, av6o^ J flower) is a word 

 in common use to designate the floral envelopes as a 

 whole, without distinction of calyx and corolla. It is 

 used in description, especially when these two envel- 

 opes are so similar as not to be readily distinguished, 

 as in the Tulip, Lily, and the Endogens generally; 

 also where only one envelope exists, as in Phytolacca, 

 Elm, etc. 



54. The essential floral organs stand within the cir- 

 cles of the perianth, and are so called because they 

 are the immediate instruments in perfecting the seed, 

 and thus accomplishing the final purposes of the 

 flower. These organs are of two kinds, perfectly dis- 

 tinct in position and office viz., the stamens and the 

 pistils. 



55. The stamens are those thread-like organs situ- 

 ated just within the perianth and around the pistils. 

 Their number varies from one to a hundred or more ; 

 but the most common number is five. Collectively 

 they are called the androeceum. 



56. The pistils (called also carpels) occupy the 

 center of the flower at the absolute terminus of the 

 flowering axis. They are sometimes numerous, often 

 apparently but one, always destined to bear the seed. 

 Collectively they are called the gynceceum. 



57. The torus or receptacle is the axis of the 

 flower, situated at the summit of the flower-stalk. It 



