Once seen a few times this is a distinctive and easy-to-recognise species due particularly to its long, fine prickles and furrowed stems. It is an adventive species, believed to be of horticultural origin, so often turns up on disturbed ground. The BSBI brambles atlas indicates that is widely recorded around the Edinburgh area, Lancashire and less so in East Anglia and Hampshire; however, this is not surprisingly just a reflection of the
home ranges of the more recently active Rubus recorders! It is quite likely that it could be found anywhere in the UK. In Hampshire it seems to do well in chalky soils around Winchester, but in my home town of Gosport I have seen it twice in more normal acidic bramble habitat.
The photo below shows a fairly compact inflorescence, though when well developed it becomes sub-pyramidal. Flowers are about 2.5cm diameter with short to long-pointed sepals, reflexed after flowering. The rachis is dark purple, like the stems, with very fine prickles. Petals are a delicate pale pink, turning white, broadly elliptical, c.13-14 x 9-10mm. Stamens are longer than or shorter than the top of the styles when viewed side on (clearly shorter in the older flower in the first photo below). Styles are yellowish-green; young carpels are hairy; the receptacle is glabrous.
Leaves are glabrous above and have crisped margins (like many other Rhamnifolii); the terminal leaflet is often nearly round in shape, and usually relatively small, c.8 x 7cm. There is a resemblance to the leaves of R. armeniacus, with which this species is likely to occur.
The whole plant is eglandular (i.e. no short or long-stalked glands anywhere, except for subsessile glands in the inflorescence), but is presumably placed in the Rhamnifolii on account of the thickly grey-felted leaflets.
The glabrous (or glabrescent) stems are a rich maroon colour, moderately robust and strongly furrowed. It is a medium-arching species, but sends up very long primocanes which start off erect. R. cissburiensis also has relatively fine prickles and similar coloured flowers, but its stems are usually a redder colour and not furrowed.