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18.
RHODODENDRON GLAUCUM, / « . #
Glaucous-leaved Rhododendron.
T ab. XVII.
Eruticulus erectos ramosus, ramulis petiolis pedunculis foliisque subtus lepidotis, foliis cllipticis seu elliptico-lanccolatis mucronatis in pctiolum
brevem augustatis superne denudatis subtus albo-glaucescentibus, corymbis terminalibus 6-8-floris, floribus suberectis medioeribus,
calycis 5-partiti lobis ovatds acutis subfoliaceis, corolloe minute glanduloso-punctatæ roseæ tubo late campanulato intus basi pubescente,
limbi lobis patentibus rotundatis emarginatis, staminibus 10, filamentis basi puberulis, ovario dense squamuloso infeme nudo, capsula
subglobosa calycem persistentem oequante squamulosa glauca 5-loculari.
Hab. Sikkim-Himalaya; rocky depressed ridges of Chola, Lachen, and Laehoong ; elev. 10-12,000. FI. May ; fr. November.
This constitutes a small shrub of the average height of two feet. Branches scarcely so thick as a goose-quill,
yellowish-brown, often glaucous-white, the younger ones squamulose. Leaves rather crowded at the extremities of the
branches, 1-3 inches long, usually 1-1^ inch broad, on short petioles, oblong or broadly lanceolate, obtuse, with a mucro,
upper side deep green, when old naked above, below remarkably glaucous, almost white, and quite dotted with copious
little scales, which in the young state covered the whole leaf, and at all times abound on the bracteas, buds, peduncles, and
especially on the calyx-segments. Peduncles seven to eight almost in an umbel at the apices of the branches, erect, an
inch or more long, rather slender. Flowers erect or inclined, pale pinkish-purple. Calyx deeply five-partite, the lobes
ovate, acute, leafy, almost the length of the tube of the corolla. Corolla rather more than an inch long, and about as
broad in the widest part: tube campanulate; limb moderately spreading, of five nearly equal rounded emarginate lobes.
Stamens ten, included: filaments downy at the base. Ovary ovate, five-furrowed, upper half densely scaly. Capsule short,
subglobose, acute, five-valved, scaly, included in the large loose persistent calyx, the valves glaucous, lepidote.
The remarkably glaucous colour* of the underside of the leaves, and the great development of the calyx, will
readily distinguish this species from every other. In foliage, indeed, it has the closest resemblance to R. virgatum : but
in that alone,—the inflorescence and calyx are widely different. The whole plant has a powerful resinous smell, due to
exceedingly minute globules of a pale yellow colour, which may be seen to exude from beneath the little scales on the
underside of the leaves, and which, in this species, too, abound so much on the other parts of the plant.
These scales, themselves, are very curious on the underside of the leaves of this plant: they are of two kinds;
the majority are smaller, pale-coloured, exhibiting several concentric circles of minute, nearly uniform cells; the larger
ones are setose at the margin, and consist of a centre or disc of small cells, while the circumference forms a limb or
margin of radiating elongated cells (see fig. 6, 7).
* This glaucous hue is fully retained in the well-dried specimens, but disappears from those that have been by any accident wetted.
Tab. XVII. Rhododendron glaucum. Eig. 1. Stamen. 2. Calyx and pistil. 8. Pistil. 4. Transverse section of the ovary:—magnified.
5. Eruit included in the calyx, and with the persistent style:—natural sise. 6. Portion of a young leaf, showing the scales:—magnified.
7. Exhibits the two different scales separated from the leaf:—more highly magnified.