245 



leaves are distinctly linear- lanceolate and bear single flowers 

 in their axils (fig. 66, A). The plant is coated with stellate 

 hairs. The leaves are isolateral with about two layers of 

 palisade cells on each side and a number of crystal-cells. 

 The midrib is surrounded by a thick sclerenchyma extending 

 often from epidermis to epidermis. The small veins are 

 surrounded by translucent storage cells. The epidermis consists 

 of one layer, not very thick-walled, and has stomata (not 

 sunk) on both sides. 



In August Ceratocarpns resembles a spiny ball (fig. 66, 

 B, C). The leaves are reduced so that only the midrib remains, 

 and even if some still seem to retain their lamina, an ana- 

 tomical examination shows that all the cells are collapsed 

 and dead. At this season of the year all the leaves are thus 

 reduced to thorns, and the 

 assimilating functions are 

 carried on by the two 

 connate prophylls which 

 form the two-thorned fruit- 

 spathes (see fig. 66 C). 

 A section of the wall 

 of the fruit-spathe shows 

 (fig. 67) that the inner 

 surface is formed of two 

 lignified thick-walled layers, 

 the second of which shows 

 no cell-cavities; beyond these skeleton-cell-layers there lies 

 an assimilating parenchyma made up of one layer of short 

 palisade cells and 1 or 2 layers of transverse cells loosely 

 arranged. All the cells are filled with starch. The veins (N) 

 are enclosed in bundles of bast above and below, especially 

 the two veins situated near the two margins of the spathe. 



Fig. 67. Ceratocarpus arenarius. Trans- 

 verse section of part of the fruit-spathe 

 (Prophyll). (X 203.) 



Cornulaca Korschinskyi Litw. 



An erect sand-desert plant thickly covered with short 

 acicular leaves (fig. 68). Each leaf-axil gives rise to a rosette- 

 shoot bearing many leaf- thorns, and in every leaf-axil, (i. e. 

 on the lower parts of the leaves) there are a great number 



