categoryZUnderShrubs UnderShrubs List 

WHITE ROCK-ROSE

Helianthemum apenninum

Rock-Rose Family [Cistaceae]

month8may month8jun month8june month8jul month8july month8aug month8sep month8sept

category
category8UnderShrubs
status
statusZnative
flower
flower8white
inner
inner8yellow
morph
morph8actino
petals
petalsZ5
stem
stem8round
rarity
rarityZrare

24th April 2009, Photo: © Phillip Bagshaw
An low under-shrub of limestone turf, but up to 50cm tall.


24th April 2009, Photo: © Phillip Bagshaw
Has brilliant-white petals with central yellow smudge and numerous yellow anthers.


24th April 2009, Photo: © Phillip Bagshaw
Flowers up to 30mm across.


24th April 2009, Photo: © Phillip Bagshaw
Five very wrinkly rather ragged petals. Petals have a central deep-yellow patch.


24th April 2009, Photo: © Phillip Bagshaw
With a hemispherical splay of deep-yellow anthers at the end of greenish-yellow filaments.


24th April 2009, Photo: © Phillip Bagshaw
Several flowers branch off a main flowering stem. Three multiply-ridged elliptic sepals cupped around the back of the petals, the ridges often reddish. Each flower has three outer sepals plus two normally hidden plain sepals, making for the reported 5 sepals all told.


24th April 2009, Photo: © Phillip Bagshaw
Un-opened flower buds with their ridged sepals. Your Author knows not what the tiny oval 'leaf-like' bracts resting at the back of some of the sepals are, but presumes they are tiny leaves.


24th April 2009, Photo: © Phillip Bagshaw
Leaves narrower than those of Common Rock-Rose and have a deeply grooved central mid-rib. The two 'halves' of the leaves divided by the groove are strongly convexly curved. The lower leaves have their stalks the same lengths as the two stipules each side (one pointing directly towards the observer). Leaves and stalks covered in short matted greyish hairs giving a matt appearance to the top leaf surface.


Hybridizes with : Common Rock-Rose (Helianthemum nummularium) to produce Helianthemum × sulphureum which has intermediately-coloured pale-yellow petals (sulphur-coloured) with leaves also intermediate in character. This hybrid is highly fertile; some garden cultivars are of such hybrids.

Flowers have some similarities to : white Roses but they are without thorns and very low under-shrubs, being somewhat woody in parts.

Many similarities to : Common Rock-Rose (Helianthemum nummularium) but these have deep-yellow petals (rather than white petals), slightly broader leaves, the leaves being hairless above and downy underneath) (rather than downy white on the top surface).

Uniquely identifiable characteristics

Distinguishing Feature :

No relation to : Roses such as Field Rose (Rosa arvensis) [a plant with similar name which belongs to the Rosaceae].

This plant is very rare, appearing in less that 5 hectads now appearing only near the coast of North Somerset and South Devon. It grows in dry limestone grassland and is native.


  Helianthemum apenninum  ⇐ Global Aspect ⇒ Cistaceae  

Distribution
 family8Rock-Rose family8Cistaceae

 BSBI maps
genus8Helianthemum
Helianthemum
(Rock-Roses)

WHITE ROCK-ROSE

Helianthemum apenninum

Rock-Rose Family [Cistaceae]