POSITIVE D^DOUBLKMBNT. 71 



plant ; here there are two extra corollas, but there is no 

 alternation, the petals of all three corollas being oppo- 

 site to one another. The middle corolla (the first extra 

 one) is less developed than the innermost and is closely 

 adherent throughout the greater part of its length 

 with that,* separating into five petals at the top ; its 

 orientation is like that of the other two. N..B. Brown 

 described (the present writer has seen the specimen) a 

 very rare case of this phenomenon in the Asclepifid 

 Stapelia revoluta ; a single fiower possessed two corolla- 

 whorls, each with its annulus (so characteristic of the 

 genus), the petals of the inner alternating with those 

 of the outer whorl. Heinricher describes and figures 

 flowers of the comfrey {Symphytum officinale) each 

 petal of which bore on its outer (lower) surface, near 

 the top of the corolla-tube, two small petaloid enations, 

 and the remarkable point about them was that their 

 orientation was normal and not reversed, as is the 

 general rule with such enations ; i. e. their upper sur- 

 faces are opposed to the lower surface of the corolla 

 which bore them ; they occurred with great regularity, 

 but tended to disappear in the younger flowers of ^Ije 

 inflorescence. The author regards them as stipules. 

 Morren described a flower of "Gloxinia" ■\ having a 

 " catacorolla," composed of a tubular union of five 

 petals not wholly resembling the normal ones in shape; 

 the orientation of the "catacorolla" is the reverse of 

 that of the normal one, the upper coloured surface being 

 directed outwards. Its component petals are opposite 

 those of the normal flower. 



There is also a well-known form of this flower in 

 which the corolla bears on its outer surface as enations 

 five or fewer distinct petals having reversed orienta- 

 tion of their surfaces (fig. 90). This phenomenon has 

 never yet been adequately explained. Morren con- 

 sidered the attached petals to be the rudiments of as 



* Masters describes the same thing in a " Gloxinia " where the stamens 

 had become changed into a gamopetalous corolla from the outer surface of 

 which petaloid enations arose. 



t Sinningia speciosa. 



