xv] 



THE WATER VIOLET 



197 



instance, is left stranded, the water leaves are apt to dry up, but 

 the ends of the shoots grow into a land form entirely different 

 in habit from the water form. It develops as a minute turf, an 

 inch high; the stems are frequently branched, the internodes 

 are short instead of being elongated as in the water form, 

 and many adventitious roots are produced from the nodes. 

 The leaves are smaller than in the submerged form, and the 

 segments are fewer, broader and thicker. 



A close connexion between submerged and aerial * forms * 

 has in recent years been demonstrated in the case of Hottonia, 

 the Water Violet. In this plant, which previous observers had 



Inflortftceue -' 



FIG. 127. Hottonia palustris, L. Diagrammatic sketch of typical land and water 

 forms. [Prankerd, T. L. (1911).] 



erroneously described as free-floating, it is now known 1 that 

 the oldest part of the rhizome is generally embedded in mud, 

 and that from it arise vertical aerial branches, which may be- 

 come detached by the dying off of the older part of the stem, 

 thus giving rise to so-called 'land forms/ which are similar 

 in anatomical structure to the submerged parts of the aquatic 

 plant, rather than to the aerial inflorescence region (Fig. 127). 

 The differences between the land and water leaves of Poly- 

 gonum amphibium^ have already been mentioned, and are illus- 

 trated in Figs. 99 and 100, p. 1 52. It is notable that in this case 



iPrankerdjT. L. (1911). 



