A low semi-shrubby plant, covering ground over 2 or 3 ft across, but scarcely rising more than 1 ft above it; the older stems prostrate, the young flowering ones erect, somewhat hairy. Leaves flat, variable in size and shape, usually oblong, sometimes approaching ovate or lanceolate, 1⁄4 to 1 in. long, 1⁄8 to 1⁄4 in. wide, green and more or less hairy above, grey or white with stellate hairs beneath; stalk 1⁄8 to 3⁄16 in. long; stipules lance-shaped, longer than the leaf-stalk. Cymes terminal, with many but successively developed flowers. Flower-stalks decurved, erect only when the flower is expanded. Flowers yellow, about 1 in. across. Sepals five, the two outer ones small, fringed with hairs; three inner ones ovate, with three or four prominent hairy ribs, the rest of the surface hairy or glabrous.
H. nummularium, in the typical state described above, is a native of much of Europe (including Great Britain), and of Asia Minor and the Caucasus, and has long been cultivated. The specific epithet nummularium, implying that the leaves are coin-shaped as in Lysimachia nummularia, is not at all apt, but it happened that the type, collected near Montpelier in the 17th century, had the lower leaves roundish, as is sometimes the case in this species.
In southern and central Europe and the Near East the species is much more variable than with us, and the numerous races have been grouped into subspecies, some of which are not very clearly demarcated.
cv. ‘Amy Baring’. – A mat-forming plant only a few inches high but eventually two or more feet across. Leaves oblong-elliptic or oblong-lanceolate, mostly 5⁄8 to 7⁄8 in. long, whitish and hairy beneath. Flowers deep yellow, darkening to orange-yellow at the centre, about 1 in. wide. This charming variety descends from a plant collected by Mrs Amy Doncaster (née Baring) while staying at Gavarnie in the Pyrenees. She gave it to A. K. Bulley, the well-known grower and collector of alpines, who was staying at the same hotel, and it was he who named and first propagated it.
subsp. glabrum (K. Koch) Wilczek H. vulgare var. glabrum K. Koch; H. grandiflorum var. glabrum (K. Koch) Rehd. – Flowers as in subsp. grandiflorum. Leaves glabrous except for scattered hairs on the margins and midrib. Alps and Appenines to the Caucasus.
subsp. grandiflorum (Scop.) Schinz & Thellung Cistus grandiflorus Scop.; H. grandiflorum (Scop.) DC. – Leaves green and sparsely hairy beneath. Flowers up to 11⁄2 in. across, golden- or orange-yellow, usually rather few in each cyme. Sepals downy on the ribs, otherwise more or less glabrous. This has a more ‘alpine’ distribution than the typical subspecies, occurring at high elevations in the mountains of S. and C. Europe from the Pyrenees to the Carpathians; also in the Caucasus. Introduced in 1800.
subsp. obscurum (Čelak.) J. Holub H. nummularium subsp. ovatum (Viv.) Schinz & Thellung; Cistus ovatus Viv.; H. obscurum Pers. – Leaves more hairy than in subsp. grandiflorum but still green on both sides. Flowers up to about 1 in. across only. Sepals usually hairy between the ribs, downy on them. Common in C. Europe and extending north to Sweden and east to Asia Minor.
subsp. pyrenaicum (Janchen) Schinz & Thellung H. pyrenaicum Janchen; H. nummularium var. roseum (Willk.) Schneid.; H. vulgare var. roseum Willk. – In foliage this does not differ much from the typical subspecies, but the flowers are pink. Native mainly of the Pyrenees and one of the parents of the garden hybrids. Two other pink-flowered subspecies occur in the Maritime Alps and the Appenines.
f. surreianum (L.) Cistus surrejanus L.; H. surrejanum (L.) Mill.; H. chamaecistus subsp. surrejanum (L.) Gross. – This curious variety is said to have first been found near Croydon in Surrey. It is distinguished from the type by the narrow petals being deeply notched at the end; they are linear-lanceolate, about 1⁄8 in. wide, 3⁄8 in. long, yellow. This variety has little beauty and is really a deformity. Similar plants have been observed growing wild in the Tyrol.
Linnaeus took the description of this plant from the Hortus Elthamensis of J. J. Dillenius, a work published in London in 1732.
subsp. tomentosum (Scop.) Schinz & Thellung Cistus tomentosus Scop., not Sm.; H. nummularium var. scopolii (Willk.) Schneid. – This is very near to the typical subspecies, but is more robust, with larger leaves, 3⁄4 to 13⁄4 in. long, 1⁄4 to 5⁄8 in. wide, and flowers up to 11⁄4 in. across. It was originally described from the S. Tyrol and is said to be common there and in the Italian Dolomites, but also occurs farther east.
Certain garden varieties figured by Sweet in Cistineae (1825-30) are near to H. nummularium and may derive from it without intermixture of any other species.