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HUTCHINSON—THE MADDENI SERIES OF RHODODENDRON. 9 
early period develop a yellowish subsequently red content 
which ultimately spreads over the whole umbo. Hence the 
change of colour in some species of the under leaf surface to a 
ferruginous tint. The pits on the upper leaf surface hardly 
deserve the name. From this surface the scales fall off early 
as a rule and the mature leaf shows scarcely an undulation to 
indicate the points of fall. At the same time a few remanent 
scales may always be found and in some cases these may be 
numerous. In Rh. Maddeni, Hk. f., for instance in cultivation 
the surface is often bronzed by them and the same may be 
seen often in Rh. crassum, Franch. On the under surface the 
pits are deeper and can always be seen even on the oldest leaves 
from which the scales have fallen. In some where the leaf pit is 
shallow and the stalk long enough to raise the umbo out of it the 
fringe is depressed ; in others the umbo is beneath the level of 
the mouth of the pit and then the fringe becomes slightly 
concave upwards—in the case ofa species like Rh. megacalyx, 
Balf. f. et Ward, where the pit is deep and the whole scale barely 
reaches its mouth the fringe is turned directly upwards. 
The scales vary in size and there seems a general tendency for 
some of them to form longer stalks and broader disks and to 
stand out well above the surface of the leaf on the under side 
especially on the larger veins. 
“ The distribution of the scales on the under side gives us a 
readily observed mark by which to diagnose species and it is 
particularly valuable for the separation of Rh. formosum, Wall. 
from other forms which have been confused with it. And here 
let me say that the distribution of the scales is correlated with 
other leaf characters which shows that their relative position 
is not fortuitous. In none of the species as yet known to me 
do the scales on the under surface of the mature leaf overlap, in 
none do neighbouring ones touch each other everywhere. A 
portion of the leaf epidermis is always visible between the scales. 
Most of the species have the scales approximating so that one 
may say there is visible as much if not more scale surface than 
epidermal surface. We may for convenience speak of this as 
a densely lepidote surface. A smaller number of forms—amongst 
them Rh. formosum, Wall., Rh. Veitchianum, Hook., Rh. Dal- 
housiae, Hk. f.—have the scales relatively far apart and the 
visible epidermal surface is far larger in area than the scale 
surface. This I designate a laxly lepidote surface. 
“‘ The leaf surface between the scales is always grey or white 
grey, the latter specially in the laxly lepidote forms. This 
bloom can be rubbed off and if one handles fresh specimens 
the fingers become greasy. The colour is due to the epidermal 
papillae with their granular coating of wax making a surface 
