222 



A restoration-shoot grown up through the sand from a 

 buried shrub of Alhagi had its subterranean part beset with 

 scale-leaves and with a yellow coating which was thick and 

 spongy to the touch. When cut through the coating proved 

 to be a thick layer of cork (fig. 50, D, E), formed from 

 a phellogen in the cortex; this was double the thickness of 

 pith, wood and inner cortex together. All the cells had 

 exceedingly thin corky walls, easily torn and all empty and 

 dead. Inside such an air-filled case the growing shoot must 

 be well protected. 



Heliotropium dasycarpum Ldb. 



An undershrub occurring in the clay-desert. It has 

 leaves 1 to 2 centimetres in length, coated with stiff hairs; 

 the foliage is so open that the whole plant is transparent. 

 The flowers appear in June and July and evidently only the 

 lower flowers of the scorpioid cyme produce fruit. The 

 achenes are long-haired and hard-shelled. 



The leaf is almost isolateral in structure. The epidermis 

 is one-layered with stomata on both surfaces and not sunk. 

 Both surfaces are coated with hairs most of which are bent 

 to one side while some are short and somewhat dome-shaped. 

 The cuticle extends over all the epidermis as a warty 

 covering. The hairs arise from large thin- walled epidermal 

 cells which contain stratified cystoliths, the so-called hair- 

 cystoliths (see SOLEREDER 1899, p. 632, fig. 127; the hairs 

 mentioned here are similar to fig. B). The upper face of the 

 leaf has one layer of long palisade cells, the lower face two 

 layers of shorter ones. Grouped around the veins in the 

 middle are some isodiametric or slightly oblong cells, trans- 

 lucent or containing a little chlorophyll. 



Frankenia hirsuta L. (= F hispida D. C). 

 This species occurs in comparatively moist localities and 

 as a rule on a saline soil. It has decumbent, lignified bran- 

 ches. The leaves are about half a centimetre long, revolute, 

 with scattered hairs and with grains of salt. The small red 

 flowers may be found still open in July. 



