Secondary Thickening in Kendrickia Walked, Hook. f. 
BY 
A. M. CLARK, M.B., B.Sc. 
Robert Donaldson Scholar , Glasgow University. 
With Plate XXXI. 
I T was suggested to me by Professor Bower that the secondary 
thickening in the stem of Kendrickia Walkeri might afford an 
interesting field for investigation. For the material on which my 
observations were made, and for much valuable assistance during the 
course of the investigation, I am indebted to Professor Bower. 
Kendrickia Walkeri , Hook, f., a member of the family of Melastomaceae, 
is an epiphytic climbing shrub, which, like the ivy, climbs by adventitious 
roots. It is found growing on the Anamallay Hills, S. India, and in 
Ceylon ‘in the forests of the lower Montane zone, and extending down 
to 2,000 ft. in the Kukul Korale .’ 1 The lower parts of the stems are 
said to be flattened with distichous leaves, but at the summit they are 
spreading, pendent, bearing leaves on all sides . 2 
Upon preparing sections of the stem, it was found that even the finest 
twigs showed a slight development of secondary thickening, which, to all 
appearance, had taken place in a perfectly normal manner. 
The arrangement of tissues in this early stage corresponds with the 
type (c) described by De Bary . 3 Here the vascular bundles form a con- 
tinuous ring, which ‘ assumes the structure of a vascular bundle ’ , no 
primary medullary rays being present. Other members of the Melastomaceae 
also possess this same arrangement. Pl. XXXI, Fig. i, represents a trans- 
verse section of a sector of a stem at this stage. In the centre of the stem 
is the somewhat large pith, containing an occasional ill-developed cauline 
bundle, which is not shown in the figure, and, projecting into the pith, 
are a number of prominent, completely separated, internal phloem-groups. 
A complete cambium ring is present with secondary xylem to its inner 
1 H. Trimen, Handbook of Flora of Ceylon, vol. xi, p. 200. 
2 Hooker, Flora British India, vol. ii, p. 526. 
3 De Bary, Comp. Anat., Engl, ed., p. 457. 
[Annals of Botany, Vol. XXL No, LXXXIII, July, 1907.] 
