CHAPTER IX. — THE TORUS, CALYX AND COROLLA. 



69 



CHAPTER IX.— THE TORUS, CALYX AND COROLLA. 



The Torus. This is the shortened axis on which the other 

 floral organs are inserted. In form it is commonly convex or 

 flat, but sometimes it is conical, as in the Strawberry, sometimes 

 long and beaked, as in the Geranium, sometimes concave or 

 hollow, as in the Rose and Fig, sometimes top-shaped, as in 

 Nelumbium, and sometimes stipitate, as in Silene and Gynan- 

 dropsis, where the middle portion is elongated into a stalk, 

 separating some of the floral whorls from each other. 



Fig. 205. 



Fig. 206. 



Fig. 207. 



Fig. 205. — Orange flower, cut lengthwise and deprived of its petals and all but one 

 cluster of its stamens, to show the hypogynous disc. a. 



Fig. 206. — Flower of Sumach, cut lengthwise, showing perigynous disc, a. 

 Fig. 207. —Flower of yEthusa, cut lengthwise to show the epigynous disc, a. 



Not infrequently the receptacle produces a fleshy outgrowth 

 from its margin, called a disc. If this remains wholly under- 

 neath the pistils, as in Fig. 205, it is said to be hypogynous ; if it 

 grows up around and partially but not wholly envelops them, as 

 in Fig. 206, it is c ailed perigynous ; and if it completely envelops 

 them and becomes adnate to them, so as to appear to spring 

 from the top of the ovary, as in Fig. 207, it is said to be epigynous. 



The axis of a flower cluster, if very short and resembling in 

 shape the receptacle of a single flower, is also called a receptacle, 

 or a common receptacle. The floral axes of the Dandelion, 

 Lettuce and Clover are examples. 



The Calyx. This is the outer of the four series of floral 

 leaves, and its parts ordinarily bear a closer resemblance to true 

 leaves than do the other organs of the flower. They are more 

 commonly green in color, and are then described as foliaceous, 



