162 



under the most favourable conditions. Thus conditions which 

 bring about a scattered growth of perennial plants favour 

 the annual ones (See for instance M. VAHL 1904 p. 67). 



The summer-annuals, fairly numerous in the Transcaspian 

 lowlands, are adapted in a different way and to different 

 conditions. The plant lives through the summer, hence it 

 must endure desiccation and is xerophytic in structure. They 

 do not die till winter sets in. 



Table 4. 



The last line in Table 4 gives the percentages of early 

 and late flowering annual plants in the Transcapian lowlands. 

 As some ephemeral plants may be seen in flower at the 

 beginning of June, I have fixed the limit at July 1. Plants 

 which may be found flowering on the first of July and later 

 are thus considered late-flowering, those which have completed 

 flowering before the end of June are termed early flowering. 

 When the flowering season of any species is unknown to 

 me, it is generally given as early flowering. This table is 

 intended to give some notion as to the proportion between 

 ephemerals and summer-annuals. Even though these defini- 

 tions do not perfectly differentiate between early and late 

 flowering, yet they do so to a certain extent. An attempt 

 was made to draw up a list of summer-annual plants, 

 regardless of the flowering season, but owing to insufficient 

 knowledge of the life-history of certain species, I shall not 

 give it here. It is noteworthy however, that 74 per ct. of 

 the (86) species flower after July 1. The division according to 

 flowering season thus makes the number of late-flowering 



