1903] Biological notes on Canadian species of Viola. 159 



the mother-plant for at least two seasons ; they commence to 

 bloom in their second year. But in no other American violet have 

 we, so far, detected rootshoots, and they are not very well known 

 among- the old world species either, Wydler and Irmisch noticed 

 them in V. sylvatica, Riviniana and canina, and Professor Warming- 

 found them in V. elatior.^ It would seem that they might be 

 found among the corresponding American homologues, viz. : 

 V Canadensis, striata and rostrata, and perhaps also in the species 

 of the group C. 



In considering the means of propagation, floral and vegetative, 

 as possessed by these Canadian species of Viola, it seems as if 

 those ot the group E [V. pritnulesjolia, etc.) are the best equipped, 

 since they produce stolons and develop seed-producing flowers be- 

 sides ; these species are, thus, able to wander and spread them- 

 selves over a larger area than the others, in which stolons do not 

 occur. Viola pedata, with its short and plump, vertical rhizome, 

 is, nevertheless, possessed of some power to wander by means ot 

 the rootshoots. But in all the other groups (B, C and D) the 

 structure of the rhizome does not enable the individual to spread 

 over any large area, and the principal distribution is in these- 

 species secured by the seeds, which are ejected with much 

 violence and thrown to a great distance by a peculiar mechanism 

 of the carpels. This manner of dispersing the seeds becomes, of 

 course, much impeded when the cleistogamic flowers bury them- 

 selves; it may be for this same reason that the bog-species have 

 their pods raised high above the wet, mossy substrate, by which 

 the dispersion of the seeds become better secured than otherwise. 



Brookland, U.C., September, 1903. 



EXPLANATION OF PLATES. 



Plate IV. 



Fig-. I — Viola Macounii. A cleistog-amic flower, mag-nified. 



Fig^. 2 — Same species. A cleistog-amic flower laid open, showing five «epal», 

 rudimentary wart-like petals, two stamens and the pistil, magnified. 



Fig:. 3 — Same species. The pistil and the two stamens in their natural 

 position, magnified. 



^ Botan. Tidsskr. Ser. 3. Vol. 2. Copenhagen, 1877-79, p. 63, and 

 Botan. Notiser. Lund., 1884, p. 32. 



