108 PROCEEDINGS OF THE ACADEMY OF [1899. 



the plant are simply the strongly developed cilia on the united edges 

 of the clasping leaf -bases. 



An interesting circumstance in connection with Fagopyrum is the 

 tendency to sterility of the flowers under certain conditions. 

 Farmers know that if buckwheat is sown early in the season, the 

 seed crop is light. Examining plants on the 22d of July, that had 

 come up from self-sown seed in early spring, out of many hundreds 

 of flowers, only one had perfected a seed. The anthers were des- 

 titute of pollen. This may have been the result of unusual vegeta- 

 tive vigor, Avhich vigor has to be somewhat checked in most plants 

 before fruitfulness is favored. The plants examined were growing 

 in very rich soil, and unusually luxuriant; but the fact shows how 

 much conditions have to do with sexual affairs. 



XI. The influexce of fdxgi ox the forms and 



CHARACTERS OF PLANTS. 



The influence of microscopic fungi in changing the form and 

 character of vegetation is well-known in connection with mon- 

 strous conditions. It does not, however, seem to have occurred 

 to biologists that what occurs in an exaggerated degree may rea- 

 sonably be expected to prevail as a rule.' The power that can in- 

 duce vegetation to run into monstrosities may be so able to control 

 its forces as to be a regular factor among the laws of form. 



I believe that Prof. Farlow and some German botanists have 

 recorded cases where the action of minute fungi has changed the 

 character of plants to a degree that might be almost termed specific. 

 I have myself, in a communication to the Academy of Natural 

 Sciences of Philadelphia (see Proceedings, 1874, p. 146) shown 

 that where Euj^horbia maculata is attacked by an JEcidium, it 

 assumes characters very little different from Euplwrhia hyperici- 

 folia. Instead of trailing, the plant becomes erect. The hairy 

 stem and fruit become perfectly smooth, and the swelHng at the 

 nodes that characterizes the latter species is assumed under the 

 changed conditions. Only for the evidence furnished b}" the 

 reproductive stage of the fungus, a botanist might well he 

 pardoned for referring the attacked specimens to Euphorbia 

 hypericifolia. Assuredly, E. maculata would not be considered in 

 the determination. 



Recently a specimen of a singular combination was placed in my 



