DISCUSSION OF ECOLOGICAL FACTOES 37 



laxiflora, Phlox divaricata, Hydrophyllum virginicum,Wasli- 

 ingtonia longistylis, Ranunculus abortivus, and a few other 

 species of lesser importance make up the entire list of herba- 

 ceous bloomers, and these, with the exception of Oeum cana- 

 dense, have completed anthesis before June 1. Plants grow- 

 ing in dense woodlands are compelled, as is evidenced by the 

 specialization and adaptation of parts, to blossom before the 

 dense foliage of the upper woody layers appears, in order to 

 secure a good exposure to light and heat. Upon examining 

 these plants, we find seven, Viola obliqua, V. scdbriuscula, 

 Carex grisea, C. laxiflora, Phlox divaricata, Ranunculus 

 abortivus, and Geum canadense, are rosette formers, two, 

 Erythronium and Bicuculla, produce bulbs, and one, Wash- 

 ingtonia, develops thickened fleshy roots. These adaptations 

 enable plants to gain an early start in the spring when maxi- 

 mum light obtains in woodlands. Similar conditions are 

 found in location IV, but not to the same extent, since here 

 the struggle for light is not so desperate, and a larger number 

 of species are enabled to secure favorable conditions. 



