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amount of chlorophyll. The inner cortex consists of large 

 groups of sclerenchyma separated by narrow bands of trans- 

 lucent cells. The cortex of the youngest branches is green, 

 but when the epidermis becomes filled with tannin the 

 branch assumes a dark-brown surface which ultimately is 

 ruptured by cork-formation. 



Alhagi Camelorum Fisch. 



One of the most common plants in Trancaspia. It looks 

 like a stumpy shrub with green branches. The aerial pf)rts, 

 however, are not persistent and in general Alhagi is doubtless 

 a root-geophyte. But as short stems are occasionally found 

 — probably rhizomes originally — from which new shoots 

 rise 10 — 30 centimetres above the ground, and as the 

 determination of Raunki^r's biological types is dependent on 

 the position of the least protected buds, I propose to classify 

 the species under the chamaephytes. 



The light-shoot of Alhagi is green and spiny. The plant 

 frequently assumes the globular form since the close-set 

 expanded branches project equally in all directions. The 

 leaves are small, at most a couple of centimetres long, 

 oblong-ovate or spathulate, and the majority fall off during 

 the early part of summer. This is especially the case with 

 the leaves developed later, whereas many of the older, lower 

 leaves persist for a long time. This is probably due to the 

 great heat and dryness of the summer which prevents the 

 perfect development of new leaves. 



All the leaf-axils except the very uppermost bear thorn- 

 branches. These are leafless and green, about 4 centimetres 

 long and with a yellow tip; only the upper thorn-branches 

 bear flowers. These branches arise not in the middle of 

 the leaf-axil but obliquely towards the cathodic side of the 

 leaf (the phyllotaxy is a Vs spiral). Many of the leaf-axils 

 of the main-shoot give rise to long-shoots beside the spine, 

 on the anodic side; these long-shoots bear leaves which also 

 subtend spines except sometimes the upper ones, more rarely 

 they bear long-shoots. 



Alhagi has horizontal roots which at intervals send out 



