- 221 — 



been frequently mentioned in the preceeding pages (e. g. pp. 

 122, 128). 



When buried by the sand axillary shoots encased in a 

 thick corky coating (see below) grow upwards through the 

 sand to the surface (comp. fig. 22 which shows a somewhat 

 similar case in Heliotropiiim). Specimens of Alhagi were 

 found where tliis had taken place twice: The first restoration 

 shoot had after burial formed a new shoot. On the other 

 hand rhizomes or roots laid bare by the sand being blown 

 away from them may form new light-shoots. 



The red flowers of Alhagi appear in isolated groups 2 — 7 

 together on the upper spines, they commence to expand in 

 June. The fruit is an jointed crooked pod, (not a lomentum) 

 with 5 — 8 joints and as many seeds; it is very light. 



The anatomy of Alhagi has been examined among others 

 by B. JoNssoN who gives a number of somewhat diagram- 

 matic figures. 



The structure of the leaf in my Transcaspian specimens 

 agrees with his description and figures. The hypoderm contain- 

 ing tannic acid on the lower surface, (see fig. 50, A) may, 

 however, be wanting. When present it is seen in sections 

 parallel to the surface to form a net-work below the epidermis. 

 The stomata are slightly sunk, the epidermis is one-layered 

 and there are 4—5 layers of short palisade cells on the 

 upper and lower sides. 



As most of the leaves fall off early, the branches are 

 well provided with assimilating tissue (fig. 50 B and C). The 

 epidermis consists of two layers, and many of the cells of 

 the inner layer contain tannic acid; the palisades are nearly 

 similar to those of the leaf and are apparently best developed 

 in the thorn-branches (fig. 50 B). 



Within the green tissue there lies a parenchyma with 

 many large cells containing tannic acid. In older branches 

 the leptome has bands of sclerenchyma on the outer side. 

 The pith is large-celled, many of its cells containing tannin. 

 The presence of tannin in fig. 50 is indicated by hatching. 

 Reference should also be made to Schube, B. Jonsson and 

 VoLKENS; the latter (tab. Ill, fig. 10) gives a transverse section 

 of an internode of Alhagi manniferum. 



