OP PERIANTH, ETC. 461 



extremities they bear crowds of imperfect flowers, in 

 which the calyx only is visible, and that only in a rudi- 

 mentary and partially developed condition. Imperfect 

 development of the whole or of some of the constituent 

 parts is more common in the case of the corolla than in 



Fig. 216. Abortion of four out of five petals, Viola tricolor, side and 

 front views. 



that of the calyx. In Arenaria serpyllifolia the petals, 

 especially in autumn, are only one fourth the length of 

 the sepals. Anagallis phoenicea, Honckenya peploides, 

 Arahis alpina. Ranunculus auricomus, Buhus fruticosus, 

 and Geranium columbinum, also frequently afford illus- 

 trations of this circumstance. 



At fig. 216 is represented a pansy in which four of 

 the five petals were very small and colourless, while the 

 lower spurred petal was of the usual size and colour. 

 In this flower the stamens and pistils were wholly 

 suppressed, and the flower-stalk, instead, of being bent 

 near the flower, retained its primary straight direction. 

 Similar atrophic conditions of the corolla occur habit- 

 ually among Violacece. 



The diminished size of the petals sometimes coexists 

 with an increase in their number, as in a flower of 

 Streptocarpus Rexii, mentioned by Bureau.^ 



Among monocotyledons this partial development 

 seems to be even more frequent than in dicotyledons. 

 In addition to the well-known cases of certain species 

 of Bellevalia and Muscari, wherein the uppermost 

 flowers of the raceme are more or less atrophied (see 



' * Bull. Soc. Bot. France,' yd. viii, 1861, p. 710. 



