18 WRIGHT : THE GENUS DIOSPYROS 



and the remainder sub-opposite, p. oppositifolja resembles 

 D. Melanoxylon in the opposite and sub-opposite arrange- 

 ment of the leaves. In the former species, however, many 

 twigs have their leaves crowded together to form large 

 rosettes. 



Form and Size of Leaves. The leaves conform to the 

 usual tropical type in that they are simple, entire, and 

 petiolate. The shape may be ovate (D. oyalifolia), lanceolate 

 (D. hirsute), or lanceolate oblong, with a tapering or abrupt 

 apex, and a rounded or tapering base. 



The size varies considerably, being smallest (30 to 70mm.) 

 in D. QQcarpa and D. pruriens, and largest (190 to 350 mm. 

 long) in D, Moonii, D. insignis, and D. Embryopteris. 

 Within the same species there is often a considerable 

 variation in size, the young leaves arising on offshoots from 

 the main stem being many times the size of those occurring 

 on the normal twigs. A case in point is in the large 

 leaves of D. Melanoxylon, these occurring on the young 

 shoots arising from the base of small trees and measuring 

 100 to 240 mm., whereas the normal dimensions for this 

 species are 50 to 100 mm. Heterophylly occurs to a 

 marked degree in D. Gardneri, D. qppositifolia, and D. 

 sylvatica. 



Venation. The vascular bundles in the leaf form a 

 central stout midrib with several smaller lateral factors 

 connected alternately along its length, these in their turn 

 being made up by the coalescence of the very small bundles 

 scattered between them. Sometimes the vascular bundles 

 project strongly on the upper surface (D. Embryopteris). 

 sometimes on the lower surface (D. insignis), but are often 

 relatively inconspicuous (D. affinis, D. montana, and D. 

 oocarpa). 



The midrib may be very conspicuous, as in D. Moonii and 

 D. acuta, or it may be insignificant as in D. oocarpa and D. 

 attennata. 



