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Helianthemum oelandicum - Hoary Rock-rose

Phylum: Magnoliophyta - Class: Equisetopsida - Order: Malvales - Family: Cistaceae

Hoary Rock-rose

An uncommon find in Britain and Ireland, Hoary Rock-rose is a perennial, low-growing or almost prostrate wildflower.

Hoary Rock-rose, closeup of flowers

Description

Borne in clusters of three to six, the flowers, which are usually 10 to 15mm across, have five well-separated yellow petals. The very hoary sepals are the most obvious distinguishing feature of this rather variable rock-rose species. The oval leaves are evergreen.

Habitat

In Britain and Ireland this wildflower is nearly always associated with dry, rocky alkaline soils; it is fairly tolerant of salty air. Helianthemum oelandicum subsp. incanum is found in coastal areas of Britain, while Helianthemum oelandicum subsp. levigatum is recorded from an inland upland site (Cronkley Fell) in Yorkshire. Another subspecies, Helianthemum oelandicum subsp. piloselloides, occurs in Ireland's Burren region.

Hoary Rock-rose, showing the hoary sepals

Distribution

In Britain and Ireland, Hoary Rock-rose is mainly a coastal plant with particular strongholds on the Gower Coast, on Great Orme and parts of Anglesey (in North Wales) and in the Burren (in south-west Ireland). On mainland Europe this member of the family Cistaceae occurs as far north as Sweden, and it is also recorded from Germany, France, Spain and several eastern European countries as well as locally in parts of North Africa.

Blooming times

In Britain and Ireland Hoary Rock-rose produces flowers very early in springtime, often from early April; its flowers are usually over by the end of July..

Etymology

The specific epithet oelandicum refers to Sweden's island of Öland, which is where Carl Linnaeus collected the type specimen in 1741.

Similar species

Common Rock-rose Helianthemum nummularium is also found mainly in limestone and chalk regions of Britain and Ireland; it starts flowering a month or so later than Hoary Rock-rose and its flowers are usually much larger than those of Hoary Rock-rose.

In the Mediterranean region of Europe, Spotted Rock-rose Tuberaria guttata is very common; it has yellow petals with distinctive red patches at their bases.

Several other members of the Rock-rose family (Cistaceae) occur in the Mediterranean region include Cistus Albidus (Grey-leaved Cistus) and Cistus salviifolius (Sage-leaved Cistus).

The Hoary Rock-rose specimens shown here were photographed on Great Orme during April.


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