156 The Ottawa Naturalist. [December 



B. Rhizome horizontal, otherwise as in A : 



V. sagittata, affinis, Macounii, cucullata, palmata, papilionacea. 



C. Rhizome horizontal or ascending, monopodial, with basal 



leaves from the axils of which aerial siems develop 

 with leaves and flowers, but no stolons : 

 V. pubescens, glabella, orbiculata. 



D. Rhizome a sympodial pseudorhizome with basal leaves, 



etc., as in C : 

 V. Canadensis, striata, rostrata. 



E. Rhizome horizontal, monopodial, leaves all basal with 



axillary flowers and stolons with scale-like leaves : 

 V. Leconteana, primulcEfolia, Selkirkii, blanda, lanceolata. 



As may be readily seen from this table, the monopodial 

 ramification seems the most characteristic, while the sympodial 

 occurs only in a few species. Of these two kinds of branching', 

 the monopodial is in Viola recognized by its continuous growth 

 in one direction and by its terminal bud developing only leaves 

 with axillary shoots : floral or vegetative, of which the latter con- 

 tinue the same development of leaves and without being terminated 

 by a floral axis. These lateral shoots, however, do not attain 

 the same length or the same strength as the mother axis, unless 

 in cases where this becomes injured and dies off^. It is thus char- 

 acteristic of the monopodium that the terminal bud remains vege- 

 tative and for an indefinite period. 



The sympodial rhizome is in Viola but sparingly represented, 

 and as a matter of fact it does not occur as a true rhizome 

 in the stricter sense of the word. We have called it a pseudo- 

 rhizome, because the under-ground stem-portion is here (in 

 V. Canadensis, etc.) only represented by the bases of the aerial 

 shoots, from the lowermost leaf-axils of which buds develop, 

 which in the following season grow out into above-groimd shoots. 

 But there is no under-ground mother-axis in these species, and, 

 moreover, each bud becomes terminated hy a floral shoot with 

 cauline leaves and axilla ty flowers. And it is seen without much 

 difficulty when we examine V. Canadensis that the fresh, flower- 

 ing shoots are, always, borne upon the base of an old, withered 

 stem from the previous year. One might suppose that V. 



