As interpreted in Flora Europaea, H. oelandicum is a polymorphic species, subdivided into five subspecies, of which the typical one (subsp. oelandicum) is confined to Oland, off the south-east coast of Sweden, and Spitzbergen. The first of the two subspecies described here is certainly in cultivation and the second may be:
subsp. alpestre (Jacq.) Breistr. Cistus alpestris Jacq.; H. italicum subsp. alpestre (Jacq.) Beger – A dainty little shrub 3 to 5 in. high, forming a tuft of dense spreading branches covered thickly with pale, minute hairs. Leaves without stipules, green on both sides, oblong-elliptic, elliptic-lanceolate, or narrow-oblong, tapered at the base, 1⁄4 to 1⁄2 in. long, up to 1⁄8 or slightly more wide, furnished with a few comparatively long hairs, especially at the margins. Flowers produced in June and July, three to six (rarely more) in a terminal raceme-like cyme, each flower 1⁄2 to 3⁄4 in. wide, bright yellow, unblotched, borne on a slender downy stalk. Sepals five, hairy, the three inner ones oval and about half as long as the petals.
Native of the mountains of C. and S. Europe, usually on limestone, extending high into the alpine zone (to 8,000 ft or more); introduced in 1818. It is quite hardy and admirable for the rock garden.
subsp. italicum (L.) Font Quer & Rothm. Cistus italicus L.; H. italicum (L.) Pers.; H. penicillatum Thibaut ex Dun. – This subspecies is mainly confined to the Mediterranean region, but is also found in the S. Tyrol. From subsp. alpestre it differs mainly in its laxer habit, its inflorescences with up to twenty flowers and sometimes branched, and in the flowers being much smaller, up to 1⁄2 in. wide. The stems are often reddish, though this may not be a constant character. It is sometimes of procumbent habit.
The typical subspecies of H. oelandicum has almost glabrous leaves and very small flowers, with petals scarcely exceeding the sepals in length. The type came from the limestone island of Öland, where it was collected by Linnaeus in 1741.
The genus Helianthemum is mainly represented in cultivation by plants of garden origin, deriving for the most part from intercrossing between H. appeninum, H. croceum, and H. nummularium, though some other species may have been involved. Many of these are near to JL nummularium, which they resemble in their flat leaves, green and sparsely hairy above; and it is possible that some of these may be the result of sporting and intercrossing within that species. But many, perhaps the majority, clearly cannot belong to H. nummularium since their leaves are covered more or less densely on the upper surface with whitish hairs, rendering them grey-green or even silvery.
A number of hybrids between the above-mentioned species were already in cultivation when Sweet published his Cistineae (1825-30), but the present garden stock is of more recent origin. The famous ‘Ben’ group, named after Scottish mountains, was raised by John Nicollof Monifieth near Dundee, who died in 1926.
The following is only a selection from the large number of hybrids now in commerce. All flower from late May until end June, with a few flowers later. For cultivation and propagation see the introductory note to Helianthemum. The plants, especially those that are of open habit, should be trimmed after flowering.
‘Afflick’. – Bright deep orange, centre brownish orange. Foliage medium green, fairly glossy.
‘Alice Howorth’. – Deep mulberry-crimson, semi-double. Foliage deep green, glossy.
‘Amy Baring’. See under H. nummularium.
‘Ben Attow’. – Pale primrose with deeper centre.
‘Ben Avon’. – Bright Tyrian-rose, base tinged orange. Foliage medium green.
‘Ben Fhada’. – Bright saturated yellow with contrasting orange eye. One of the most popular of the ‘Ben’ group.
‘Bengal Rose’. – Rose-red. Grey-green foliage.
‘Ben Hope’. – Carmine-red. Foliage grey-green.
‘Ben Ledi’. – Deep Tyrian-rose. Foliage dark green.
‘Ben Lui’. – Bright crimson, tinged orange at the centre. Foliage dark green. A.M. 1925.
‘Ben More’. – Flame-orange. Foliage glossy.
‘Ben Nevis’. – Orange-yellow with a bronzy crimson centre. Dark leaves. Compact habit. A.M. 1924.
‘Ben Venue’. – Bright scarlet orange, centre darker. Foliage dark green. A.M. 1924.
‘Cerise Queen’. – Rose-pink, double. Said to be an improvement on ‘Rose of Leeswood’.
‘Fireball’. – Bright bronzy orange, centre orange. Foliage dark green. A.M. 1925.
‘Fire Dragon’. – Bright orange-scarlet. Foliage grey-green.
‘Henfield Brilliant’. – Bright brick-red. Grey foliage.
‘Jubilee’. – Primrose-yellow, double. Dark green foliage. A.M. 1970.
‘Mrs C. W. Earle’. – Scarlet, double, the petals yellow at the base. Dark green foliage.
‘Mrs Clay’. – Orange-red with a darker centre. Foliage grey-green. A.M. 1970.
‘Rhodanthe Carneum’. – See ‘Wisley Pink’.
‘St John’s College Yellow’. – Bright golden yellow with orange centre. Grey-green foliage. A.M. 1925.
‘Sudbury Gem’. – Flowers deep pink, with a flame centre. Foliage greyish.
‘The Bride’. – What is believed to be the true variety is of low, compact habit, with grey rather short leaves; flowers white with a small yellow blotch. It was sent to the recent trials at Wisley and is also grown at Kew.
‘Tigrinum Plenum’. – Tawny orange, double.
‘Watergate Rose’. – Rosy-crimson tinged with orange at the centre. Foliage grey-green. A.M. 1932.
‘Wisley Pink’. – Pale pink with an orange centre. Grey foliage. Very beautiful but of rather sparse habit and dropping its petals early in the afternoon. In the report on the Trials held at Wisley 1924-5 this was bracketed with ‘Rhodanthe Carneum’ and the two were said to be very alike.
‘Wisley Primrose’. – Flowers bright primrose-yellow. Foliage grey-green. Compact, very vigorous. A.M. 1970.