1
crystallinnm (J. Hooker), should be encouraged in its growtli
at the very edge of tides or sand-shores, where with Cakile
maritima, Mesembrianthemum australe, and M. æquilaterale,
it will form one of the most effectual first impediments to the
influx of sea-sand.
Rhamnus catharticus, Linné.
The Buckthorn. Middle and South Europe, North Africa,
Middle Asia. I t can be utilised as a hedge-plant. The
berries are of medicinal value, as indicated by the specific
name. Tbe foliage and bark can be employed for the preparation
of a green dye.
Rhamnus chlorophorus, Lindley.
China. From the bai'k a superior green pigment is prepared,
B. ntilis, from the same country, serves for the like purpose,
This kind of dye is particularly used for silk, and known as
Lokao.
Rhamnus Græcus, Reuter.
Greece. From this shxaib, and to no less extent from the
allied R. prunifolins (Sibth.), are the green dye-berries
collected in Greece, according to Dr. Heldreich. These
shrubs grow on stony mountains np to 2500 feet.
Rhamnus infectorius, Linné.
On the Mediterranean Sea and in the countries near to it.
The berry-like fruits of this shrub are known in commerce as
Graines d’Avignon and Graines de Perse, and produce a
valuable green dye. Other species seem to supply a similar
dye-material, for instance R. saxatilis (L.), R. amygdalinus
(Desf), R. oleoides (L.), R. tinctorius (W. and K.)
Rhapis flabelliformis, Linné fil.
China and Japan. This exceedingly slender Palm attains
only a height of a few feet. The stems can be used for
various small implements. I t is one of the best plants for
table decoration.
Rhaponticum acaule, Candolle.
On the Mediterranean Sea. A perennial herb. The root is
edible.
Rheum australe, Don.* (R. Emodi, Wall.; R. Webhianum,
Royle.)
Himalayan regions up to 16,000 feet. From this species at
least a portion of the medicinal Rhubarb is obtained; most
likely several species furnish Rhubarb-root, and its quality
depends probably much on the climatic region and the geologic
formation, in which the plant grows. Should we wish
to cultivate any species here for superior medicmal roots,
then clearly localities in our higher and drier alpine tracts
should be chosen for the purpose. Hayne regards the presence
of much yellowish pigment in the seed-shell as
indicating a good medicinal Rhubarb-plant. As much as
five lbs. of the dried drug are obtained from a single plant,
several years old. An important orange-red crystalline
substance, Emodin, allied to Crysophanic acid, occurs in
genuine Rhubarb.
Rheum officinale. Bâillon.*
Western China and Eastern Thibet on tbe high tableland.
I t furnishes the most of the true Turkey Rhubarb, not merely
from tbe root, but also from the woody stem. Suited for our
Alps.
Rheum Rhaponticum, Linné.
From the Volga to Central Asia. This species together with
R. Tataricum (L. fil.), R. undulatum (L.) and a few others,
all Asiatic (one extending to Japan), provide their acidulous
leaf-stalks and unexpanded flower-mass for culinary purposes.
Rhubarb-leaves can also be used in the manner of Spinage.
R. palmatum (L.) often considered to yield the best Rliubarb-
root, is an insular plant of North-Eastern Asia, but may in
the alpine deserts far inland become a source of the genuine
root, so long ascribed to it. That is the only one wibli
deeply-jagged leaves.
Rhododendron maximum, Linné.
North-East Ameiica. Attains a height of twenty feet.
Irrespective of its being a fine acquisition for any garden-
copses, this bush seems of industrial importance, because Mr.
C. Forster asserts that tbe wood of this and the allied
Kalmia latifolia (L.) is equalled only by the best boxwood.
This may give a clue to other substitutes for that scarce commodity,
needed so extensively by the wood-engraver.
Rhus caustica. Hooker and Arnott.
Chili, where it is called the Litre. A small or middle-sized
tree, the very hard wood of which is used for wheel-teeth,
axletrees and select furnitui'e. The plant seems neither
caustic nor otherwise poisonous (Dr. Philippi).
Rhus copallina, Linné.
North America, extending to Canada. A comparatively
dwarf species. This can also be used for tanning. A resin
for varnishes is also obtained from this sbrub.
Rhus coriaria, Linné.*
The Tanner’s Sumach. Countries around the Mediterranean
Sea. The foliage of this shrub or small tree, i-educed to
powder, forms the Sumach of commerce. Many localities in
our colony are particulai'ly well adapted for the growth of
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