1903I Biological notes on Canadian species of Viola. 153 



(fig-, g), and there are three stamens (fig'. 12), of which, however, 

 only two have both nnther-cells developed. One of these stamens 

 has always, as in the preceding- two species, the connective folded 

 around the style and stig^ma, as shown in figure 10, and the 

 structure of the anthers and the connective is identical. The 

 cleistogamic flowers are in this species, V. sagittata^ constantly 

 raised above ground on erect peduncles of quite considerable 

 length, and it appears as if the position oi these peculiar little 

 flowers might constitute, if not a specific, then at least a sectional 

 character. And in looking over the several species in which 

 cleistogamic flowers occur, we notice that some of the acaulescent, 

 woodland types : V. papilionacea, Macounii, and villosa show a 

 tendency of burying the flowers in the ground, while the bog 

 plants : V. sagiiiata, blanda, lanceolafa, prunulcEfolia^ affinis and 

 cucullata Aways bear the cleistogamic flowers on erect peduncles; 

 on the other hand, V. eniarginata and ovata, both inhabitants of 

 sandv, gravelly hillsides, bear the flovve s raised above the 

 ground. This varied position observed in the cleistogamic 

 flowers depends evidently upon the character of the substrate : 

 humus, wet boggy ground or gravelly soil, besides that, the 

 atmospheric conditions may not be excluded. If the flowers and 

 fruits of the bog species were buried in the wet moss, they would, 

 no doubt, be exposed to decaying, and it seems very natural that 

 V. affinis always bears these flowers raised above ground, when 

 it occurs in swamps or wet meadows, while it partly buries them 

 in ihe ground, when growing in thickets, border of woods, etc. 



Very peculiar is the mode of growth observed in V. lotuiidi- 

 folia. The perfect flowers ar.^ in this species plainly developed 

 from the axils of the basal leaves : acaulescent, while the cleisto- 

 gamic are borne in the axils of cauline leaves : caulescent ; it 

 appears as it the stems which bear the cleistogamic flowers in this 

 species are mostly subterranean, but we have seen one instance, 

 however, where a stem bore a few green leaves instead of merely 

 scale-like. In Viola orbiculata it is interesting to see that two 

 sets of aerial stems with green leaves and flowers develop in the 

 same season, and that the flowers of the first set are perfect and 

 very showy, though sterile, while the later developed are all 

 cleistogamic and closed, but produce seeds. 



