— 242 — 



Cousinia. 



Many Transcaspian species belong to this genus, most 

 of them perennials. They are all rather broad-leaved, thorny, 

 and frequently "cobweb-haired". C. annua and C. dichotoma 

 were examined as examples of annual species. The former 

 I found flowering in the sand-desert during the hottest time 

 of summer. It was about half a metre high and had broad 

 spiny leaves the axils of which bore rich dense inflorescences. 

 The plant is glabrous, the stem snow-white and glossy. 



The leaf is somewhat dorsiventral with two layers of 

 palisade cells on the upper side and one on the lower, and 

 a rather loose spongy paranchyma. The veins have bast- 

 strands, the larger ones projecting as ridges on the lower face. 



They lie several together, quite 



~ separate or connected by a trans- 



~~^ V/ "^ — ^V_ lucent aqueous tissue which merges 



^-^ \_J) d? O Q outwards into a collenchymatous 



, v_J)^- — \ o O ^ tissue. 



*— '/- — X CD <^ The epidermis is rather thin- 



-N K^ V-^0 ^^ walled and has stomata on both 



''^ ^ — S- — ^r A^_^Q sides, slightly sunk. 



'' ' The stem is without green 



Fig. 65. Cousinia arinua Epi- ^^^ ^^d has a thick epidermis 



dermis and collenchyma of stem. ' ^ 



(X 203). over a deep thick-walled collen- 



chyma (fig. 65) all the way round. 

 Cousinia dichotoma is a smaller plant which may still 

 be found flowering at the beginning of July, but it begins 

 to wither about this time. The broad, spiny leaves still 

 pi-eserve their form and position because well-provided with 

 sclerenchyma; they are somewhat dorsiventral and have 

 stomata (not sunk) on both faces as in C. annua. 



Frankenia pulverulenta L. 



A slender plant with decumbent branches. Like F. 

 hirsuta (see p. 222) it occurs most frequently on somewhat 

 moist soil. The leaves are small and flat with salt-crystals 

 on both faces; the glands which are figured by Solereder 



