32 ANTHOLOGY: THE GENERAL NATURE OF THE FLOWER 



ovary upon which the ovules develop is the Placenta (Fig. 10, a). The 

 hollow portion of the pistil, containing the placentae and ovules is the 

 Ovary (Fig. 9, b). The divisions of the ovarian cavity, which sometimes 

 exist, are called Cells (Fig. 221, etc.), and the partitions which separate 

 them are called Septa or Cell walls. A point upon a pistil (Fig. 9, d) 

 which lacks its epidermis and permits entrance into the ovary of the 

 pollen-product is a Stigma. (See also Figs. 191, etc.) A portion con- 

 necting the stigma to the ovary, narrower than the latter and usually 

 not hollow, is the Style (Fig. 9, c). 



The leafy nature of the Carpel and its products is well illustrated 

 by Fig. 19, which represents a reverted state of the pistil. 



The Essential Organs. — Since the androecium and gynaecium are 

 capable of producing seeds without the necessity for other floral parts, 

 they are commonly known as the Essential organs, others as the Non- 

 essential organs. 



Protection Needed by the Essential Organs. — The danger of accident, 

 as the result of blows, punctures, erosion, or even changes of tempera- 

 ture, to the complex mechanism and delicate structure of the essential 

 organs, and the resulting necessity for their protection, is obvious. In 

 the case under consideration the flowers are so closely crowded upon 

 their supporting branch that their leaf-scales (which are not parts of 

 the flowers, but grow out underneath them, from the nodes) afford 

 , the necessary protection. But commonly this is not the case, and each 

 flower must provide and possess its own protecting organs. It must be 

 borne in mind, however, that protection is usually the least important 

 office which such organs fulfil. 



The Calyx. — A series, or apparent or real circle, of such modified 

 leaves, underneath or surrounding the androecium, is displayed in the 

 flower of Pulsatilla (Fig. 16, a) and constitutes its Calyx, frequently 

 indicated by the symbol K, the several leaves being called either Sepals 

 or Calyx-Lobes, in accordance with conditions to be considered hereafter. 



The Corolla. — Commonly, there is a second series or circle between the 

 calyx and androecium, as in the buttercup (Fig. 17, a), and this is called 

 the Corolla, frequently indicated by the symbol C, its several leaves, 

 Petals or Corolla-lobes, according to their condition. Rare cases 

 occur in which, although but a single circle is present, it is regarded as 

 a corolla. 



Sinuses. — The space between two adjacent petals or corolla-lobes — 

 and the same is true of a similar space between any two organs or 

 divisions standing side by side — is called the Sinus. 



