298 The Plant World. 



SOME EFFECTS OF PROTRACTED DROUGHT UPON 



XEROPHYTIC PLANTS. 

 By Frank C. Gates. 



From the beginning of the growing season until the latter 

 part of August, 1910, there was a very pronounced deficiency 

 in amount of rainfall in the Upper Lakes Basin which resulted 

 in imposing severe and unusual conditions upon the plants that 

 grow on the beach. Ample opportunity was thus given for 

 observing the external modifications that such conditions would 

 bring about. Many differences were noted, but as far as could 

 be determined they were in relative degrees of characters normal 

 to the plants. Abundant proof was given of the power of beach 

 plants to quickly and seemingly easily respond to a change in 

 edaphic conditions which had taken place within the life of each 

 individual plant. 



Taking up in greater detail a few of the commoner plants, 

 the following table sets forth some of the more noticeable changes. 

 Euphorbia corollata.- — The pubescence, which is usually shed at 



flowering time, remained through flowering into fruiting; 



stems thicker and red; leaves somewhat shorter and nar- 

 rower. 

 Salsola kali tenuijolia. — Lateral roots usually well developed, 



(7-10 feet long for a plant 3 inches high); leaves wider and 



shorter; plants more succulent and hairy. 

 Corispermum hyssopijolium. — Roots longer and stronger, plants 



more succulent. 

 Cakile edentula. — Even more succulent than normally. 

 Euphorbia polygonijolia. — Stems and leaves thicker and more 



succulent. 

 Salix syrticola. — Leaves one-half to two-thirds shorter and a 



trifle narrower. 

 Potentilla anserina. — Stems much thicker and densely villous- 



pubescent, intemodes of the runners much shorter. 

 Juncus balticus littoralis and Scirpus americanus. — Scarcely a 



plant but whose stem was spirally twisted. In general 



much the same could have been said of nearly any plant 



on the beach. 

 Chicago, III. 



