and relatively dry air were applied to opposite ends, a polar 

 growth resulted with reference to these conditions only and not 

 with reference to what had been basal or apical in the twig be- 

 fore separation from the tree. Apparently, possible leaves failed 

 to be formed in water without much air and possible roots failed 

 to be formed in air without much moisture. 



In many of the above experiments twigs of an undetermined 

 native willow were used in the bundles with weeping willow and 

 without different results. The assumption that the weeping wil- 

 low has acquired these innumerable centers of new growth as a 

 means to produce new trees when branches happen to be broken 

 off, may not be in the line of fundamental explanations to be 



sought for. 



Johns Hopkins University, 

 Baltimore, Md. 



NOTES ON SOME SOUTHERN ILLINOIS 

 PLANTS. — Ill 



By H. a. Gleason 



The two species o^ Jnssiaca which extend into Illinois, y. diffusa 

 Forsk. and /. dccjirrcus (Walt.) DC, are of characteristically 

 austro-riparian habit, and are always found in swamps or along 

 streams. The former species is well distributed along the Mis- 

 sissippi on muddy banks with a gradual slope, and is able to live 

 farther down the bank towards the water than any other plant 

 except Eragrostis Jiypnoidcs. It is nowhere common and has so 

 far not been observed except along the river. Jiissiaca dccnrrens, 

 on the other hand, is not found on the Mississippi side, but only 

 along the Ohio River and its tributaries. It is very abundant 

 among the Tertiary hills in ^Massac and Pulaski counties, and 

 along the small streams flowing southward through the Car- 

 boniferous and Devonian regions in Pope and Hardin counties. 

 The limited amount of field work done north of the Ozark uplift 

 has not as }-et revealed its presence there. 



Jiissiaea deauTens is of some interest because of the develop- 

 ment of aerenchyma upon its subaquatic roots. This peculiarity 



