338 S. Reginald Price 
The material dealt with here was gathered on the Ain Sefra sand 
dunes. The plant is an annual. The roots form a small tuft at 
the base of the stock, and descend vertically into the sand to a 
depth of three or four inches. The root hairs are long and persistent, 
and at first sight there appears to be a sandy sheath. Closer 
examination of the soaked out material, however, shows that there 
is no sheath of the type found in the two species of Aristida. The 
grains of sand seem to be held more especially by the long tangled 
root-hairs which project freely into the sand around. Some grains 
show a close contact with the outer layers of the cortex, and this 
fact, together with the large number of grains held, very possibly 
indicates that a certain amount of mucilage is secreted here, 
although this was not actually demonstrated. 
SCHISM US CALYCINUS L. 
This is also a small annual grass found in the Mediterranean 
region and in North Africa. 1 The herbarium material shows a 
spreading habit, with a small bunch of adventitious roots at the base, 
penetrating the sand to a depth of three or four inches. The root- 
hairs clothe the whole length of the roots, and are remarkably long. 
Tbe large amount of sand brought away with each root, appears to 
be due rather to the entangling of the grains by the long root-hairs 
than to the presence of mucilage. At any rate there is no attempt 
at the formation of a definite cemented sheath, and the grains do 
not seem to adhere to the outer cortex to any extent. 
HORDEUM MURINUM L. 
What is apparently a sand form of the common barley-grass of 
waste places was collected from the dunes of Ain Sefra. The species 
grows generally in arid places in Europe, North Africa, America, &c. 2 
The plant is an annual and the roots are very similar to those of 
Schismns cnlycinus just described. 3 The root-hairs are very long, 
and persist throughout the whole length of the root, while sand 
grains are entangled by these hairs in much the same way. 
III. GENERAL CONSIDERATIONS. 
From the examples dealt with and also from those mentioned 
by Volkens, 4 it seems that the persistence of the root-hairs is 
1 Boissier, l.c., p. 597. 2 Boissier, l.c., p. 686. 
3 cf. Cannon “ Root Habits of Desert Plants,” Carnegie Instit. 
Publication, 131, 1911, p. 34. 
4 Volkens, l.c.. p. 25. 
