290 BRITISH FLOWERING PLANTS chap. 



is concealed by the woolly hairs on the inner side of the 

 corolla, and the dilated filaments of the stamens. When 

 the bud opens, the anthers are ripe, but not the stigmas, 

 which, moreover, project considerably. Self-fertilisation 

 is therefore at first excluded, but eventually the flower 

 bends over, and the stigmas come within the fall line of 

 the pollen (see Pyrola, p. 265). 



In Nova Zembla, according to Ekstam, the plant is 

 protogynous. The flowers bend over in wet weather. 

 The capsule is upright, and at maturity it ruptures along 

 the middle of the dissepiments, so that the outer cell- walls 

 break away from the central axis. The seeds thus lie 

 in a cup, and are jerked out by the wind. They are 

 dark brown, elliptical, convex on the back, flattened on 

 the ventral aspect, and more or less finely rugose. 



CONVOLVULACE^ 

 CONVOLVXJLTJS 



Flowers brightly coloured and adapted to various 

 insects ; generally only open for a single day. Corolla 

 plaited in the bud, and rolling inwards when it fades. 

 Honey secreted at the base of the ovary. Many of the 

 exotic species have extrafloral nectaries. As in other 

 climbers, the growing part of the shoot revolves or 

 " circumnutates " from right to left [i.e. against the 

 course of the sun), and in this species makes a revolution 

 in about two hours. Other plants move more rapidly. 

 The vine revolves in about an hour, Cobcea scandens 

 {a member of the preceding order) in only twenty-five 

 minutes. We have three species of Convolvulus. C. 

 arvensis has small, the other two have large bracts, and 

 are sometimes separated as the genus Calystegia ; C. 

 septum has the leaves angular at the base, and the 

 corolla white ; while in C. Soldanella the leaves are 

 rounded, and, as in so many other seaside plants, fleshy, 

 and the corolla pink. 



