LRO, 
diaceae both annuals and perennials. These plants do not 
die or go to rest till the autumn. SCHIMPER calls such plants 
“Ground-Water Plants”. 
Another group of plants satisfy their water-requirements 
from the precipitation of the winter and spring, the melting 
snow and rain-water which is stored in the upper layers of 
the soil. When the dry hot time comes (in May—June) most 
of the available water (Chresard) from these strata evaporates, 
and they become very dry. What water remains becomes 
more concentrated and saline through evaporation (BERNATSKY 
p. 209), and as the plants dependent on the water in the 
upper layers — the Spring-Plants — are not xerophilous 
or only slightly so, the increasing heat soon makes them 
wither. Before this takes place, however, their development 
is finished, and they have dispersed their seeds. Most of the 
spring-plants are annuals or ephemerals, as VOLKENS terms 
them, but there are also some bulbous plants and other 
perennials, especially in the more favourable localities. These 
perennials go to rest when summer comes, and assimilate 
and bloom only in spring. 
This distinction between a spring-vegetation and a sum- 
mer-vegetation has long been known for many deserts and 
steppes. (It is also present, though perhaps less pronounced, 
in the whole region of temperate winter-rains). GRISEBACH 
(1872 I p. 449) has already recorded Artemisia as one of the 
few perennials (“Stauden”) which vegetate through the sum- 
mer, and he also states that most annual plants die quickly 
during the spring, whereas some annual Chenopodiaceae live 
through the summer, blossom in the autumn, and do not 
die till the frost sets in. — The spring-flora of the South- 
Russian steppe has been described among others by GRUNER 
and TANFILJEW, that of Egypt by Vorkens, and that of the 
desert-territory of western North-America by Mac Douai, 
THORNBER and others. Here we find two maxima of ephe- 
meral plants corresponding to the two rainy seasons of winter 
and summer. 
We shall first describe the Transcaspian Clay-desert in 
its Spring aspect, and afterwards attempt to present a picture 
of the more sombre aspects of Summer and Autumn. 
