CHAP. I.] YTOLACEiE. 279 



themum, Sun-rose, is very appropriate, as the 

 flowers will only expand in sunshine, and will 

 even decay in the bud without opening at all, 

 when gloomy weather lasts for several days. 



ORDER XX. VIOLACE^— THE VIOLET TRIBE. 



The order Violaceae, though not a large one, 

 contains several genera, but the most interesting 

 is the genus Viola, which includes among many 

 other species the Sweet Violet {Viola odorata), 

 and the Heartsease (V. tricolor). The flowers 

 of both species have many claims to admiration, 

 but they do not add the charm of regularity in 

 construction to their other attractions, as, in 

 fact, few flowers are less symmetrical. The 

 flowers of both are nearly alike in their details; 

 but to avoid confusion, I will describe them 

 separately. The calyx of the Heartsease con- 

 sists of five pointed distinct sepals, two of them 

 rather smaller than the others. These sepals 

 are not attached, as in most other plants, at 

 their base ; but so as to leave nearly a quarter 

 of their length standing up, far beyond the 

 place where they are fixed to the receptacle, 

 so as to form a sort of border or cup round 

 the stem, and between it and the flower. 

 The sepals are green, but they are edged 

 with a delicate whitish membrane at the mar- 

 gin, scarcely to be seen without a microscope. 



