RHQ 
RHO 
still more recent date, by which the 
genera Rhododendron and Azalea were 
found to mingle, gave a new impulse to 
their culture, and by the employment of 
yellow-tinted Azaleas in the production 
of hybrid seed, a strain of primrose 
colour has been imparted to the Rhodo¬ 
dendron. The genus contains about 
twenty hardy species, some of them 
natives of the coldest mountain regions, 
such as R. ferrugineum , hirsutum , and 
Caucasicum, terminating the ligneous 
vegetation of Alpine districts; the last is 
found within a short distance of the 
perpetual ice on the higher points of the 
Caucasus, and the others abound on the 
Alps of Switzerland, Austria, Piedmont, 
and Savoy. The stronger-growing kinds, 
such as maximum, chrysantlmm , yonticum , 
and clauricum, are found only on sub- 
alpine regions, inhabiting the damp spots 
and fissures of mountain sides, considera¬ 
bly lower than the preceding; next 
beneath them occur catawbiense, Camt- 
schaticum , and arborea, and in proportion 
to the altitude of their natural stations, 
the plants are found more robust; those 
of the lower range, though annually sub¬ 
ject to much frost, and consequently 
hardy enough to bear our climate when 
in a mature state, commence growing 
and flowering a month too soon to render 
their progress secure or satisfactory; our 
late spring frosts frequently ripening the 
recent developments. Such kinds, there¬ 
fore, as are naturally disposed to bloom 
before May, should be planted with a 
northern exposure, and if screened altoge¬ 
ther from the south, their summer growth 
and autumnal ripening are retarded 
so far as to have an effect on the flower- 
buds, which, in that case, are expanded 
full a fortnight later, and so at a safer 
time. The attention of cultivators being 
directed to this matter, has resulted, as 
before remarked, in the production of 
varieties in which the native habit is 
overruled, and the blooming deferred till 
danger from frost is quite passed, and 
with ordinary attention in the choice of 
sorts and situation, an array of splendour 
throughout the month of May is now to 
be regarded as certain in the common 
average of seasons. Rhododendrons, 
though natives of elevated places, do not 
seem benefited by exposure to the direct 
rays of the sun, or to be improved by 
being allowed the best place in the gar¬ 
den : a gentle northern slope, with a 
slight screen on the southern side, ap¬ 
pears to be a situation they delight in, 
and one that exhibits their beauties in 
the greatest perfection; in a hot sunny 
place the foliage is often scorched, the 
growth stinted, and the flower-heads few 
and small—all these effects being traceable 
to the influence of excessive heat and 
drought upon the roots. The soil usually 
prepared for them is peat or bog-mould; 
but as this varies considerably in texture 
and quality, it may be well in some cases 
to make an addition either of sand or 
loam, according as the principal material 
is more or less compact or porous ; heavy, 
close-grained bog-mould, with but little 
vegetable matter in it, should be lightened 
by adding sand or leaf-mould, and that 
procured from heaths or commons is 
often too open for the purpose, and may 
be improved with a proportion of strong 
loam, the object being to supply the 
roots with a medium sufficiently loose in 
texture to allow of their penetrating it 
easily in every direction, at the same 
time it must be so compact as to retain 
the necessary degree of moisture. The 
fibres of these plants being very delicate, 
will not bear extremes of any kind, and 
an observance of this peculiarity will best 
enable the operator to judge of the fitness 
of his soil. They will grow in certain 
kinds of loam that are friable and loose, 
quite as well as in peat, though the dif¬ 
ficulty in procuring the former of the 
exact quality necessary has led to the 
more frequent use of peat. The plants are 
now more extensively raised from seed 
than by any other method, though both 
layers and cuttings may be employed; 
the first method involves more time, but- 
there is the probability of originating 
superior varieties to compensate for the 
extra trouble. The splitting of the 
pericarp indicates the seed to be ripe, 
and it should then be gathered, pre¬ 
serving it in bags till the following spring, 
when it may be sown in pans of light 
heath-mould, pressed rather firm and 
