74 



ORGANOGKAPHY AND GLOSSOLOGY. 



bearing at its base two ovules with a gaping micropyle ; after fertilization, these 

 carpels thicken, harden, and become appressed, and form closed cavities which 

 protect the seeds during their ripening. 



TORUS, DISK, NECTARIES. 



The torus is the part of the receptacle situated between the calyx and the 

 pistil 011 which the corolla and androecium are inserted. It is merely the periphery 

 of the receptacle, and not a special organ ; but for convenience of description it is 

 so considered. 



The torus produces, besides stamens and petals, nectariferous glands and sundry 



442. Columbine. 

 Piutil surrounded by 

 scales. Torus showing 



the scars left by 

 the stamens (mag.). 



443. Tree Peony. 

 Flower without the corolla 

 and most of the 8tameua. 



444. White Water-Lily. 



Pistil and cup bearing the petals 



and stamen*. 



445. Orange. 

 Vertical section of pistil 



and receptacle. 

 T, tnnis ; c, calyx. 



expansions analogous to petals or stamens. Thus, in the Columbine (fig. 442), between 

 the andro3cium and the pistil, are ten membranous silvery white scales, with folded 

 edges, larger at the base than at the top, which may be considered as filaments, and 

 which sometimes bear an anther at their extremity. In the Tree Peony (fig. 443), 

 the thick swollen torus elongates into a membranous cup surrounding the carpels, 

 without adhering to them, and open at the top to afford a passage 

 to the stigmas : it appears to form a part of the fruit, from 

 which it is nevertheless very distinct. This petaloid involucre 

 sometimes bears anthers. In the White Water Lily (fig. 444) 

 the stamens and petals cohere with the torus, which envelops 

 the ovary, so that they appear to adhere to the ovary; they 

 die after flowering, leaving the torus marked with their scars. 

 In the Yellow Water Lily, the thick cup, externally green and 

 flaccid, which some botanists have considered as a torus envelop- 

 ing the ovary, is nothing but the epicarp of the ovary; at 

 maturity it bursts irregularly, and comes away, leaving the seeds retained by the 

 endocarp, when they fall to the bottom of the water and germinate. 



The torus often forms, below the ovary, a projecting ring or swelling, from 

 which spring the stamens and petals (Orange, fig. 445 T ; Mignonette, fig. 446); but 

 more often this ring, reduced to its most simple form, only appears as a circular line 



44C. Mignonette. 



Flower without corolla 



(mag.). 



