146 CARROLL— ON DEVELOPME^JT OF 



conditions seem to be a moderate amount of shade with moist, but well- 

 drained ground. Plants growing in poorly drained or marshy situa- 

 tions behave as if under adverse conditions. The small plants already 

 noted as growing under such conditions showed evidence of adverse 

 enviroment in their height, color, foliage and flowers. The giant speci- 

 mens noted above, on the other hand, cannot be said to grow under 

 optimum conditions for the species, since the production of flowers was 

 decidedly meager in most cases observed. The optimum conditions 

 for flowering are not found when the running water is washing the roots 

 of the plant unless they are situated in a slight shade, or even in the 

 open sun. Much of the material used in investigating the histology 

 was collected from several open sunny localities where the plants were 

 never shaded, along several tributaries of Darby Creek, near Phila- 

 delphia. The plants were exceedingly crowded, three to four feet in 

 height, and densely covered with flowers. In the other localities, the 

 plants were close to running water on well-drained banks; all were 

 characterized by exceedingly dense growth of plants and great abun- 

 dance of flowers. 



The species flourishes also in much drier situations. Plants were 

 noted above as growing on a hill top in open woods; these were several 

 hundred yards from running water or marshy ground. Along one of the 

 drives in Fairmount Park, Philadelphia, a quarter of a mile from the 

 nearest brook and in full sun, except in the later afternoon, a dense 

 group of plants was kept under observation during the summer of 1916. 

 The plants were thirty to thirty-six inches in height and produced both 

 cleistogamous and chasmogamous flowers in abundance. On a sunny 

 bank in the botanical gardens of the University of Pennsylvania num- 

 erous plants have maintained themselves for several years. These are 

 stocky plants averaging four feet eight inches in height and five inches 

 in circumference. From the lower nodes there are circles of adventi- 

 tious roots. These plants bear abundant, though rather small, chas- 

 mogamous flowers during August. All these plants noted grow in rich 

 soil, but the species is also to be found in poorer, sandy soils. It is 

 met with in the sands of the New Jersey Pine Barrens. Experimentally 

 also the plants were grown in poor soils. Seedlings transplanted to 

 five-inch pots of sand maintained themselves quite as well as those 

 transplanted to pots of rich soil, although they produced as a rule fewer 

 chasmogamous flowers. 



The color of flowers and stems is subject to considerable variation. 

 The flowers are typically yellow to orange-yellow dotted with brownish 



