THE TORUS 



33 



Petals and Sepals. — ^Occasionally the petals will be numerous, forming 

 more than one circle. A petal or sepal is normally not composed of 

 distinct parts, unless it be by a narrowed insertion, called the Unguis 

 or Claw, which is frequently present (Fig. 18, a), the broad part being 

 called the Lamina, Blade, or Limb. It is then said to be Unguicu- 

 late. Usually the form of sepals and petals is more obviously leaf-like 

 than that of the stames and carpels, and frequently in color and texture, 

 particularly of the sepals, they are strongly foliaceous. The calyx and 

 corolla may, however, possess any color or texture and they may be 

 similar or dissimilar, usually the latter, in this feature. The petals, as 

 well as the sepals, may even differ among themselves in color and texture. 



Fig. 16. Flower of Pulsatilla, subtended by epicalyx, with calyx of 6 sepals; a, torus; 6 and c, rudi- 

 mentary or aborted petals. 17. Flower of Adonis, a, petal; b, pistil; c, stamen. 18. Unguiculate 

 petal of Dianthus. u., unguis or claw. 19. Flower with its carpel partly reverted to the leaf-form. 



The Perigone. — The calyx, or the calyx and corolla together when both 

 exist, constitute the Perigone, less aptly called the Perianth or Floral 

 Envelopes. A flower possessing both calyx and corolla is called 

 Dichlamydeous; one with calyx only, Monochlamydeous, indicated 

 by Co, and one with neither, Achlamydeous or Naked, indicated by 

 Ko-Co. Those which have no corolla are called Apetalous. 



The Complete Flower. — A flower possessing calyx, corolla, androecium, 

 and gynaecium is called Complete. 



The Neutral Flower. — Some plants habitually produce a portion of 

 their flowers without essential organs (Fig. 268, a). Such flowers are 

 called Neutral. 



The Torus. — It must ever be borne in mind that all these parts are 

 constructed of the modified leaves of the floral branch. The latter is 

 called the Torus or Thalamus, or, less desirably, the Receptacle. The 

 torus may, therefore, be defined as the reduced branch which gives origin 

 to the parts of the flower (a, in Figs. 16, 23, and 24). 

 3 



