— 182 — 
trary a thick-walled hypodermal layer, and only one palisade 
layer. 
With Calligonum Caput Medusae are related the other 
species of this genus which grow in Transcaspia, see the 
plant-list p. 154. Borszczow has described many species; 
as to the systematic value of these I have no definite views. 
Variations are especially common in the fruits, but there is 
also considerable variety in height and in usefulness as 
sheltering plants. PALEZzZKI states that most of the species 
have a tendency to lose their branches in summer, a result 
of the heat of the sun. This shows itself first as rust- 
coloured spots which gradually make their way through the 
branches. Calligonum eriopodum is the species which suffers 
least from this injury, it is also of high stature and being 
hardy in several respects it is more extensively used in 
planting shelter-belts than the other species. Calligonum 
arborescens is also employed on account of its size, it is 
said to attain a height of 6 metres. 
Calligonum plants are raised in the nursery; one-year- 
old specimens are about one metre high. They can only 
endure water as seedlings during the cotyledonary stage. 
Under natural wild conditions Calligonum Caput Medusae 
and C. Pallasii (= Pterococcus aphyllus) seem to be the most 
common. The fruits of the latter have eight broad wings 
instead of tufts of setae (fig. 28 C). All the species have thin 
assimilation-branches. 
Ephedra alata Dene. (= E. sirobilacea Bge.). 
I have seen this plant in the sand-desert as a shrub 
one foot high, but it is said to become much higher. Part 
of a stem I saw was 14 centimetres in circumference. 
The leaves are membranous and sit three and three 
together at the joints. The year-shoots may grow long, they 
are placed laterally on the previous year-shoot, and arise 
one, two or three together. Some nodes may for several 
successive years be the starting point of new branches which 
thus form bunches. My notes include no other observations 
on the shoot-structure. 
