- 93 — 



may also be found. The rhizomes are sometimes laid bare, one 

 I saw being 132 centimetres long and only attached at one end, 

 but still living. When the plant is buried by sand, a new aerial 

 shoot is formed from an axillary bud of one of the higher 

 leaves and terminates in a rosette on the sand. (Fig. 22). But 

 these shoots do not endure the sand-drift very well, and I have 

 seen specimens buried again which were dead. The long rhi- 

 zomes may be regarded as a means pt defence; with the 

 aerial shoots widely distributed tliere is always a possibility 

 that some of them may escape destruction by the sand-drift. 

 The hairs on the leaves also probably give some protection 

 against bruising by sand. 



Living in the Sand-deserts are also a number of plants 

 of the type of Salsola Kali, i. e. spiny hard plants with a 

 limited amount of assimilation tissue. These include both 

 annuals and perennials, mostly the former. The following 

 are the most noteworthy amongst those I have seen. 



Horaninowia iilicina (fig. 70) is an annual. From the 

 summit of the long straight lignified root, there arise a 

 number of stems 20 — 30 centimetres in length, which lie on 

 the surface of the ground. The leaves are opposite, acicular 

 and spiny, and bear in their axils dwarf-shoots or long-shoots. 

 The dwarf-shoots appear as bunches of thorns (see figure 70) 

 and when long-shoots are formed they bear the groups of 

 thorns. Should this plant be covered by sand, the dwarf- 

 shoots elongate and become long-shoots, which struggle to 

 reach the light, while the main-shoots may be seen to change 

 their direction and to grow obliquely upwards, until they 

 again emerge above the surface. 



In more favourable places the species has longer leaves 

 and is more erect (var. longifolia). The leaves and young stems 

 are coated with stiff, viscous hairs amongst which sand- 

 grains are often retained ; these hairs must limit the mechanical 

 effects of the sand-drift. 



Agriophyllum minus (fig. 72) is also an annual. Large 

 specimens become strongly branched. The leaves are grass- 

 like flat, dry, multicostate, stellate-haired and thorny-pointed; 

 all bear dwarf-shoots like bunches of thorns, or long-shoots 

 which carry the thorny shoots. The leaves more especially 



