174 Kraemer : Morphology of the Genus Viola 



secreting appendage which projects Into the petal. The anther 

 cells arc introrsc and possess a characteristic collencliymatic thick- 

 ened cell in the mesophyll After fertilization and the develop- 

 ment of the fruit the slight filament attaching the stamens to the 

 calyx is ruptured. 



The ovary is half superior, about 3 to 4 mm. long and pos- 

 sesses three parietal placentae on each of which 15 to 24 ovules 

 are borne wdiich are arranged in about four transverse rows. The 

 odd one of the three carpels lies between the two spurred stamens. 

 In some cases as in K odorata and V, scabrhisada the ovary is 

 covered w^ith hairs. 



The style is hollow, is either bent or straight, of either nearly 

 uniform thickness or becoming gradually of greater diameter to- 

 wards the apex. It is persistent and scarcely projects above the 

 appendages of the stamens. The stigma is more or less head- 

 like and hollow, in some cases of scarcely greater diameter than 

 the style. In most cases it is, however, much larger and provided 

 with a beak-like extension which projects in the direction of the 

 petals and stamens, that have a sac-like or spurred appendage, and 

 possesses at the apex an opening for the entrance of the pollen 

 grains. There is also in some cases a posterior projection which 

 may be quite prominent as in V. palustris and V. priviulacfolia. 



The fruit is a tricarpellary capsule discharging its seeds in dry 

 weather by a sudden dehiscence. 



The seeds are elliptical in shape (17x9 mm.) and when ripe 

 of a yellowish-brown color; they possess a slight caruncle. 



Stigma in Detail. 



In the following species slight papillae are found on the outer 

 surface of the stigma : K arcnana, V. blanda^ K lanccolata^ K 

 odorata, V. ovata, V, palustris, K pedata, K prinmlacfolia, V. ob- 

 Hqua, K palniata, V, rosirata, V. rotiuidifolia, V, sagittata, V. Sti- 

 kirkii, V, sororia and V. striata. 



Both papillae and hairs arc present on the outer surface of the 

 stigma in the following : V. Canadensis, V. ddphinifolia, V. 

 hctcropliylla, V. hastata, V. Labradorica, V. lutca, V. Niittallii, V. 

 ptibcscens, V. scabrhisada, V. striata, V. tricolor and its varieties 

 and V. tripartita. 



