364 



Of course (lie elliptical shape is not constant witli any individual, 

 but often passes into the ovate form or becomes oblong (in this case 

 the symmetry is preserved), the leaf-base varies between rounded and 

 wedge-shaped. Young plants of C. ^f/avescens have lanceolate leaves. 

 The few known leaves of C. Jitiioiv.ikii (a. mountain-species) are likewise 

 lanceolate and piovided with a long droppiiig-point. C. montuna (a 

 monntain-species from Borneo) has on several twigs elliptical and 

 oval leaves with rounded base, and lanceolate, acuminate leav'es. 

 C. Hatninii (the xerophilous species above-mentioned) has the tip 

 ending in a very short hard macro. For the lest the leaves of all 

 species have a clearly markeil acumen, sometimes very short. 



2. The consistency of the leaf of old plants and twigs is thin- 

 leathery, the colour of the upper surface is glossy dark-green, of the 

 lower surface lightei' green with dark-green veins, in a dry condi- 

 tion haid and in herbaria as a rule brittle. Of young plants (see 

 aho\'e) they are much thinner, in sicco almost membranous (in 

 vivo herbaceous). C'. Janowskii (see above) has likewise thin ones. 

 When drying the leaves always change their coloui' to yellow or 

 yellow-green, more or less mixed with sepia-brown, the upper-surface 

 is as a rule dark-brown or olive-brown 153 — J55 (Code des couleurs 

 de KiJNCKsiEK et Valktte). For C olacifonnis 183—188 or 193, or 

 paler 217; for C. Hammii 202 — 217, for C. fiavescens the colour of 

 tiie np|)er-surface frecjuently 114, of the lower-suifaco 153. 



3. With respect to the diagnosis of the genus as well as the 

 species the nervature of the leaves, though showing common char- 

 acteristics for all species, is of some importance. The nervature of 

 the leaves is penniform, and the secondary or lateral veins never 

 start from the median nerve opposite to each other at the same 

 level, their number being as a rule I'ather small, 2 or 3 or 4 on 

 each side. In many species tiie secondary veins next to the tip do 

 not start above the middle of the median nerve, so that the upper 

 half of the leaf is mainly supplied by tertiary veins. Besides they 

 start at unequal distances from each other and are closest to each 

 other at the leaf-base, the lowest two (or sometimes one) starting 

 close to or even from the leaf-base; in consequence of this they 

 resemble triplinerved and trinerved leaves [Ficus, Cinnamonum, 



Viburnum). There often starts from the leaf-base on one or both 

 sides a secondary vein so thin, that it may be counted among the 

 tertiary veins and may easily be overlooked ; yet it follows in its 

 course the stronger veins. After starting from the midrib these 

 go upward in a wide curve till close to the edge, next about 

 parallel with the edge towards the apex. The two foremost veins 



