This species is largely confined to the southern counties of Devon, Dorset and Hampshire, but has also been recorded from scattered localities in South Wales and the rest of southern England, with one record from Ireland mapped in the brambles atlas. It is a low-growing species, favouring heathy sites. The dark, blackish-purple stems are its most distinctive character.
The panicle (above) is slightly flexuose, with a compact head composed of a relatively small number of flowers (c.2cm in diameter) and similar clusters of 3-7 flowers on the short side-branches. The rachis is dark purple like the stems, strongly downy with frequent short-stalked glands, together with acicles, pricklets and longer declining or slightly curved prickles.
Petals are stated to be white in Edees & Newton, but the photos above show that they can be distinctly pink in bud; however, these plants may be atypical or belong to a different entity which closely resembles R. melanodermis. Petals are broadly elliptical, c. 9 x 5 mm; some in these photos appear somewhat narrowed or pointed at the tip, but others are rounded. The stamens are just longer than the top of styles. Styles are pale yellowish-green, though Edees & Newton note that they may be red-based. In one specimen examined the carpels were hairy (with frequent short hairs and a few long hairs), and the receptacle had some long hairs.
Sepals are greenish-white felted with a narrow white border, long-pointed, loosely-reflexed and sometimes becoming patent. Glands on the sepals are sparse to numerous and very short-stalked, so are not noticeable amongst the hairs; a few short acicles may rarely be present. Edees & Newton also remark that the sepals are greenish-white within.
The stems are often procumbent, and bear leaves with 3-5 leaflets. In the open the leaflets usually become strongly plicate and thick in texture; they are dark green in colour. They are thinly pubescent above. The terminal leaflet is c.7 x 5 cm or larger, obovate and usually distinctly truncate above with a medium to long cuspidate tip (usually c.1.5 cm) and an emarginate or narrowly cordate base. The petiolule is relatively short. Leaflet margins are coarsely and unevenly serrate, but sometimes broadly and shallowly serrate.
Leaflets are softly and thinly hairy below, becoming
hard with age (the term used by Edees & Newton to mean the opposite of softly hairy).
Stems are almost round to bluntly angled in cross-section, deep reddish or purplish in colour, becoming darker with age and blackening in herbarium specimens. The first two shots below are taken of the same plant, one with flash and one in sunlight. They are glabrescent (sparsely hairy at first), with frequent long prickles on the angles and abundant smaller pricklets and acicles on the faces. The prickles tend to be gradually narrowed from the base, declining or slightly curved, with yellow tips. Glands are mostly subequal, sparse to numerous (presumably not numerous enough to warrant this species being placed in the Radulae).