Kraemer : ^Morphology of the Gexus Viola 177 



Violaccae. This would clistini^uish the group from the Rinorcae 

 and possibly Papayroleae, altliough of the latter no specimens have 

 been examined. 



The pecuh'arity in shape of these mucilage cells was considered 

 by the author for some time as having in themselves a diagnostic 



specific value. But in only a few instances is this the case and 

 further study is necessary here. 



A Consideration of some prominent Characters of the 



Genus. 



For the full comprehension of the significance of the various 

 parts of the plants of a genus and the value to be given to their 

 similarity or dissimilarity in structure, considerable study must 

 necessarily be given to many plants from rather widely separated 

 areas. 



F 



1. As we look upon this genus we find that whether we are deal- 

 ing with annuals, biennials or perennials, climatic influences play 

 an important part, as Kcrncr has shown that where annuals do not 

 have sufficient warmth to produce seeds (as in Alpine regions) the 

 plants arc transformed into perennials. 



2. As to whether plants are caulescent or acaulescent the re- 

 suits of Kerner, as well as the author's own observations, w^ould 

 lead us to believe that they are dependent largely also on climatic 

 conditions. Kerner found that the number and length of inter- 

 nodes that plants produced are dependent on the climate in which 

 they are growing. , Some plants of J7o/a tricolor L., van vulgaris 

 Koch which were gathered in October, 1895, on the top of an ex- 

 posed mountain near the Struth Forest in Germany, were exceed- 

 ingly dwarfed in every particular and resembled but slightly cau- 

 lescent plants. On planting them in garden soil they become a 

 foot high and in every w^ay showed a stronger development. 



w 



3. Some species produce an addition to the spring flowers, 

 cleistogamic flowers. It is not unusual for some plants in other 



orders to produce in the fall or late summer months cleistogamic 

 flowers. These are produced when the grass and various other 

 plants have grown up and the spring flowers would very likely, at 

 this time, be passed unnoticed by the insects which might assist in 

 their fertilization. This would correspond to the investigations of 



