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 ot defence; with the 
aerial shoots widely distributed there 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 ulicina (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 
