Roots of Some Rosaceous Genera. 



65 



studied, smaller quantities are found in the uniseriate than in 

 the multiseriate layers, and in the arborescent than in the 

 herbaceous or shrubby genera. The amount of starch varies 

 with the time of year in which the roots are studied. 



6. Pigment is found in all the Rosaceous genera investigated. 

 This may be present either in the cell walls and contents of 

 the uniseriate layers, the cells of the sloughing-off layers, or 

 throughout the cell cavities of all the cells. In the species 

 studied, the amount of pigment differed according to the time 

 of year in which the roots were obtained. 



7. Comparison of the few species of root and shoot observed, 

 indicate a similar structure of the periderm in each ; when the 

 stem is of equal age with the root the suberization is greater. 



8. Results of these investigations upon the periderm indicate 

 a possible evolutionary relation of the groups of Rosacea. 



Fig. I 

 Fig. 2 



Fig- 3 

 Fig. 4, 



Fig- S 

 Fig. 6 



EXPLANATION OF PLATE X. 



T. S. root of Pottntilla norvegica, X 3°°°- 

 T. S. root of Geum atro$anguineum, X 300°. 

 T. S. root of Agrimonia Eupatoria, X 300°- 

 T. S. root of Agrimonia parviflora, X 300°. 

 T. S. root of Akhemilla pyrenaica, X 3°°°- 

 T. S. root of Spiraa Filipmdula, X 300°. 



