— 189 — 
branches are arranged in bunches (A. Ammodendron, hyrcanus 
and perhaps others). 
My knowledge of these Astragalus-species is mainly 
derived from literature and herbarium material. 
Halimodendron argenteum D. C. 
A shrub attaining a height of about 2 metres, which 
prefers clayey soil. It is also common in the neighbourhood 
of rivers and is often met with in oases, by roadsides and 
such places. It has long, hori- 
zontal roots from which aerial 
shoots issue at long intervals. 
The year-shoot seems to 
become completely lignified and 
to remain alive throughout its Fa 
whole length. The primary Fig. 35. Halimodendron argen- 
Bas is green, the secondary leum. Part of transverse section 
of a year-old branch: P, Pith; 
brown. Within the bark and V, Wood; Phl., Phloeum; €. Cork. 
oF the De hel . The black part is sclerenchyma. 
Surrounding the branch there 1s The largest sclerenchyma - band 
a circle of six large bast-bundles — belongs to a leaf-rachis thorn, 
fi 35 tl eee j the next largest to a stipular 
(fig. 35), three larger ones on Horn x 31, 
one side corresponding to the 
nearest leaf above with its two stipules, and three smaller 
ones on the other side corresponding to the next but one 
set of leaves higher up. All the bundles disappear at a 
distance about 1'/z nodes below the leaf from which they 
issue. The lower part of each node of the stem has there- 
fore only three bast-bundles. The rachis of the leaf and the 
stipules form thorns, and the larger bundles of sclerenchyma 
in the bark are the downward prolongations of the thorns. 
The intervening spaces are not quite regular as the leaf-arran- 
gement is a ”/5 spiral. The structure of the bark (and the 
pith) has been described by B. Jonsson (p. 31) who has 
found mucilage-cork and air-lacunæ; I have not examined 
these. Jönsson calls the persistent leaf-rachis a thorn-branch 
bearing leaves arranged in pairs and accompanied by second- 
ary thorns. The real condition is that the leaves are pinnate 
with four cuneate leaflets. The rachis remains as a thorn 
