214 ORGANOGRAPHY. 



centripetally ; hence, here the general inflorescence is definite, 

 the partial inflorescence indefinite. In Labiate Plants we have a 

 directly reverse arrangement {fig. 370), for here the individual 

 clusters or verticiUasters open their flowers centrifugally ; but 

 the general inflorescence is centripetal; hence the general in- 

 florescence is indefinite^ while the partial inflorescence is de- 

 finite. 



Section 2. Of the Parts of the J'lower, and their Ar- 

 rangement IN the Flower-bud. 



In common language, the idea of a flower is restricted to that 

 portion in which its gay colours reside, but botanically, we 

 understand by the flower, the union of all the organs which 

 contribute to the formation of the seed. We have already stated 

 that the parts of the flower are only leaves in a modified con- 

 dition, or rather the analogues of those organs, or homologous form- 

 ations adapted for special purposes ; and that hence a flower- 

 bud is to be considered as the analogue of a leaf-bud, and the 

 flower itself of a branch, the internodes of which are but slightly 

 developed, so that all its parts are placed in nearly the same 

 plane. The detailed examination of this theoretical notion of a 

 flower will be reserved till we have finished the description of its 

 different parts or organs, when we shall be better able to under- 

 stand it, as well as other matters connected with its symmetry, 

 and the various modifications to which it is liable. 



1. Parts of the Flower. — A complete flower consists of 

 the essential organs of reproduction, enclosed in two particular 

 envelopes which are destined to protect them. These essential 

 organs are called Stamens {fig. 422, ec), and Pistil {fig. 422, 

 sti). The floral envelopes are termed Calyx {fig. 421, c), and 

 Corolla {fig. 421, p). The extremity of the peduncle or pedicel 

 upon which the parts of the flower are placed, is called the 

 Thalamus or Receptacle {fig. 422, r). The floral whorls are situ- 

 ated within each other in the following order, proceeding from 

 without inwards:— 1. Calyx, 2. Corolla, 3. Stamens, 4. Pistil. 



The Calyx {fig. 421, c) is the outer envelope or covering of 

 the flower. Its parts are called Sepals, and these are generally 

 green, and of a less delicate texture than the parts of the corolla. 

 They bear commonly a great resemblance to the true leaves. 



The Corolla {fig. 421, p), is the whorl or whorls of leafy 

 organs situated within the calyx, and forming the inner en- 

 velope of the flower. Its parts which are called Petals, are 

 frequently decorated with the richest colours j by which cha- 

 racter, and by their more delicate nature they may be usually 

 known from those of the calyx. 



The calyx and corolla are sometimes spoken of collectively 

 under the name of Perianth or Perigone {fig. 424). This terra 

 is more particularly applied to Monocotyledonous Plants, where 

 the floral envelopes generally resemble each other, and are usu- 



