R. S. Adamson. 
150 
NOTE ON THE ROOTS OF TERMINALIA ARJUNA, BEDD. 
By R. S. Adamson. 
[Text-Figs. 3-7.] 
The material examined was collected by Mr. I. H. Burkill, near 
Sembadow, in the Satpura Hills of Central India, from the banks 
of the Sipra River, and sent by him to Professor Seward, who 
handed over to me for investigation. 
Tenninalia Arjuna Beddome is a large tree belonging to the 
natural order Combretaceae,' and growing to a height of sixty to 
eighty feet. The species is confined to India and Ceylon, where it 
occurs commonly along the banks of streams and rivers. 2 
From the trees growing on the banks of a river, certain roots 
grow out horizontally into the river bed, among the stones, or just 
below the surface of the water. From these roots lateral branches 
are given off that rise vertically to the surface of the water or mud. 
It is such roots that I have investigated. The rivers in the district 
from which the material was obtained dry up during the hot season, 
when they are represented by a series of pools. The material was 
collected in October, 1908, when the level of the river was beginning 
to fall, and beneath all the trees of Tenninalia Arjuna was a thick 
growth of the small apogeotropic roots among the stones and mud 
of the river bed. 
In some of the deeper pools, as Mr. Burkill states in a letter, 
the horizontal roots bend up till they reach the surface of the water, 
where vertical roots are produced; they afterwards bend down again. 
Structure of the Horizontal Roots. 
The roots seem to be primarily triarch, though other primary 
strands appear later, so that older roots are hexarch to octarch. 
Large vessels are produced in the secondary wood, but do not 
occur in that formed previous to the activity of the cambium. 
The medullary rays consist of a single row of cells, or are 
rarely two to three rows of cells in breadth ; r they broaden out 
slightly in the phloem, owing to the greater breadth of the cells in 
that region. The phloem consists of three kinds of cells: (i.) sieve- 
tubes and companion cells, (ii.) large numbers of parenchyma cells 
1 Hooker, J. D. Flora of British India. 
2 Brandis, D. Indian Trees, 1906. 
