= Die — 
has 3—4 vessels and a leptome group, while down both 
sides there is a strand of sclerenchyma. 
The anatomy of the leaf has been described in the 
closely related, perhaps identical species, Aristida pungens, by 
DuvaL Jouve (tab. 17, fig. 7) and Tscnirch (tab. 6, fig. 3). 
The Transcaspian specimens examined by me agree in their 
chief features with what has been found by these authors, yet it 
seems to me that the single cell-layer of the green tissue has 
a more pronounced palisade-form, and that the whole leaf 
has larger internal air-cavities than in the figures cited. Some 
figures of the structure of the leaf are given in fig. 64. The 
leaf can roll up towards the inner (upper) surface which has 
long hairs, and the epidermis includes hinge-cells. Like all 
Paniceae, the plant has the veins surrounded by a starch- 
sheath which is open on the leptome side in the larger 
veins, while round the smaller ones it is interrupted on both 
sides; this again is surrounded by a palisade layer. In my 
specimens the lower surface is also furrowed, though faintly, 
and in the furrows opposite the air-spaces amongst the 
green tissue of the “prisms” there are stomata which are 
slightly sunk; other parts of the epidermis are covered with 
short, pointed hairs (fig. 64, B, C). 
E. Therophytes. 
It has been repeatedly stated in previous pages that some 
of the Therophytes are ephemeral spring-plants, while others 
— the smaller number — are summer-plants which persist 
through the dry, warm summer. The following includes 
observations on some of the species belonging to the latter 
group. The ephemeral species might likewise repay a careful 
investigation, for instance their variability as to xerophilous 
structure, depending on the soil and time of development, 
would be well worth examining. The material available 
did not, however, permit of such an investigation, particularly 
as regards anatomy. But the summer-plants seem to me 
more interesting, and during the journey my attention was 
chiefly directed towards them and towards collecting material 
of them. 
16 
