'20 



STRUCTURAL BOTANY. 



53. Perianth (tfe<3 around, avdo<r, flower) is a word in com- 

 mon use to designate the floral envelopes as a whole, without 

 distinction of calyx and corolla. It is used in description, espe- 

 cially when these two envelopes 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 circles of the 

 perianth, and are so called because they are the immediate in- 

 struments in perfecting the seed, and thus accomplishing the final 

 purposes of the flower. These organs are of two kinds, perfectly 

 distinct in position and office viz., the stamens and the pistils. 



55. The stamens are those thread-like organs situated just 

 within the perianth and around the pistils. Their number varies 

 from one to a hundred or more ; but the most common number 

 \sfive. Collectively they are called the androecium. 



56. The pistils (called also carpels) occupy the centre 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 gynoecium. 



6 Flower of the Strawberry. 6, Flower of the Pink. 7, Flower of the Lily (Lilium superbuni). Tho 

 pupil will point out the parts. 



57. The torus or receptacle is the axis of the flower, situated 

 at the summit of the flower-stalk. It commonly appears a flat- 

 toned or somewhat convex disk, whose centre corresponds to the 

 apex of the axis. On this disk, as on a platform, stand the floral 

 organs above described, in four concentric circles. The gyiue- 



