200 JOURNAL, BOMBAY NATURAL HISTORY SOCIETY, Vol. XX. 



weed in dry places all over Tropic Asia, Africa, Australia, and America. 

 Celosia argentea has an almost equally wide distribution and is a common field 

 plant in India. Alternanthera sessilis is fond of damp places throughout the 

 hotter parts of India and Ceylon. The stem structure of the Amarantacecp 

 is similar to that of the Ficoidece in having concentric rings of vascular tissue 

 (see Solereder and others). 



The Graminem cited are all of very wide distribution and inhabit all sorts 

 of situations. Dalzell and G-ibson give Eragrostis inter rupta as occurring in 

 waterholes in Gujarat. 



The analysis of this Association brings to light one or two curious facts. 

 The first is that, in one Association, we have, growing side by side^ — 



(1) plants of limited habitat and xerophytic or halophytic type— 



Tamarix species. 



(2) plants of general xerophytic type — Trianthema. 



(3) plants of the open field and of no distinct type — the grasses, com- 



posites, and Amarantacece other than Alternanthera. 



(4) plants of distinctly hygrophytic type — Ammania salicifolia, Alter- 



nanthera sessilis. 



The occurrence of a general xerophytic type along with the tamarix is to be 

 expected. The occurrence of the plants of the open field shows that these 

 have a long range of adaptability. The occurrence of hygrophytes points, I 

 think, to an invasion of odd dampish corners by plants accustomed to these 

 situations. 



A second interesting fact is that all the plants associated with the tamarix 

 are plants of exceedingly wide distribution throughout the tropics. Wide dis- 

 tribution of a species indicates considerable flexibility of constitution, and it is 

 precisely such plants that one would expect to find in conditions so trying and 

 special as those among the tamarix. 



A third point is the occurrence of the several Amarantacea, and of Trianthe- 

 ma, all with anomalous stem anatomy. I hardly think we can as yet say that 

 this structure means any' special advantage in gaining a foothold in unusual 

 situations. 



