Helianthemum is a genus of modest little evergreen shrubs or
semi- shrubs which, in an unassuming way, are attractive at all seasons. When
in bloom, however, they are among the most floriferous, vividly coloured, and
spectacular of all dwarf shrubs. The elegant and graceful little flowers are
often compared to cistus, or even to miniature single roses. Their relatively
late and prolonged flowering season makes them particularly valuable
for the rock- garden, as they are at their maximum beauty when all the earlier
flowering plants such as alyssums, aubretias, iberis, etc., have finished. They
are also ideal for planting in dry walls, on terraces, or alongside stone
steps.
Helianthemums are native to the Mediterranean regions, Asia
Minor, North America, and Europe as far north as Sweden. The name derives from
the Greek helios and anthos , with allusion to the yellow blooms.
Although profusely and continuously produced, the flowers last only one day,
from sunrise to sunset. The plants are also real sun-lovers, preferring a
rather dry, poor, even arid sandy soil which is slightly alkaline ,
in a very well-drained position. Among the one hundred or so species can be
found specimens that thrive in the semi-desert areas of Asia and North America;
while in Europe they are found growing in the mountains up to an altitude.They
are small evergreen shrubs of dwarf semi-prostrate wide-spreading habit.
Planted in dry walls or on steeply sloping ground among rocks, the plants
assume a trailing, almost prostrate habit. They do not require any special
cultural treatment but are not hardy. It is advisable to cut the plants back
severely—reducing the size by about a half—after flowering in late summer The
helianthemums grown in gardens are mostly of hybrid origin, with a wide range
of colours and with single or double flowers.
Propagation can be effected from seed sown in flats or pots
in cold- frames or unheated greenhouses in spring, or by means of cuttings of
half-ripened growths in July, which should be placed in sandy soil in frames.
Helianthemum
Chamaecistus Mill.
Native to Europe, particularly Sicily, Corsica, and other
Mediterranean regions. A small shrub with little linear-oblong opposite leaves
with recurved margins. Elegant little five-petalled single flowers; generally
yellow, but variable in colour and sometimes pink or white. Although its
maximum height is only about fully
developed plants often have a diameter of up to with a close compact habit.
Helianthemum glaucum
Pers.
Native to Southern Europe. Distinguished from other species
by its silver-white foliage which contrasts well with the small yellow single
flowers. The leaves are also thicker in texture, downy on the undersurface, and
hairy on the upper surface. It is these three species (H. apenninum, H.
Chamaecistus, and H. glaucum) that have been instrumental in creating the vast
number of garden hybrids now available.
Helianthemum
Tuberaria L.
Native to Southern Europe. A dwarf semi-shrub almost with
the habit of a herbaceous perennial. Leaves oval,, finely dentated, covered
with white hairs on the undersurface. Flowers in diameter, yellow, single, and
borne in loose terminal groups. Petals slightly dentated at the tips.
Helianthemum Hybrids
These are the Rock Roses most frequently grown in gardens.
There is a wide selection of silver- and green-leaved forms and varieties, with
single or double flowers ranging in colour from orange, yellow, or white to
pink, red, or scarlet. Specialist nurseries catalogue at least thirty named
varieties, all of which must, of course, be propagated by vegetative means from
cuttings.
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