Rubus atrebatum – Series Hystrices
back to Alphabetical index · Taxonomic index
A typical Hystrican with key features being the white flowers with narrow petals and a roundish, coarsely serrate terminal leaflet. It has a distribution centred on north Hampshire and Surrey, with scattered records around the Greater London area and outliers in Dorset, north Norfolk, Yorkshire and southern Scotland; also recorded from Belgium. Most records are probably from heathland, but most of these photos were of a single colony on somewhat nutrient-enriched habitat on clay-with-flints at Walbury Hill in north-west Hampshire.
A low-arching species typically growing to no more than about a metre in height. Panicles are pyramidal in shape with a rounded head of flowers on stout, widely divergent branches. The panicle is leafy below and often also with a few single leaflets in the panicle which are ovate or lanceolate in shape with an entire base.
A particularly well-developed panicle from Walbury Hill is shown below. In shady or infertile habitats panicles would be much more poorly developed. The rachis is slightly flexuose.
The rachis and floral branches are densely hairy with frequent long, fine prickles which are slightly to strongly declining (some more than 45°), yellow with red bases. There are also numerous short-stalked glands, gland-tipped acicles and pricklets.
Flowers are about 2-2.5cm diameter. Petals white, obovate with gradually narrowed base, c.10-12 x 5-6mm (or as small as 9 x 4.5mm), somewhat upturned giving the flower a cupped
appearance. Sepals are downy with abundant fine prickles, acicles and glands. They have long, often leafy-pointed tips and are patent both at flowering and after the petals drop, when they turn reddish inside. Stamens are distinctly longer than the styles, filaments are white and styles pale yellow-green, carpels glabrous.
Leaves in this species appear to be mainly ternate, but some have three leaflets with an additional budding leaflet, or occasionally 4 or 5 complete leaflets. The leaflet margins are coarsely compound serrate to incised, with a pleated or corrugated appearance due to the impressed secondary veins (which perhaps appear a little more widely spaced than in most other brambles). The terminal leaflet is about 6-8cm long x 6-7cm wide, ovate or nearly round in shape. The apex is moderately long, acuminate, often turned to one side, and the base usually narrowly cordate.
Leaflets are sparsely hairy above and dark green in colour. The older leaves on the open-grown bushes shown here were all a matt, slightly greyish-green above, but the youngest, fresh leaves were bright yellow-green with striking reddish-brown margins serving to accentuate the incised and undulate toothing on the margins. Long hairs are also visible on the margins. This appearance is very distinctive but is also seen in several other brambles. Some of the older leaves retained a narrow dark purplish margin.
Leaflets are softly hairy below, pale yellowish-green in colour. These ones had noticeably long hairs on the veins.
The first-year stem is well armed with frequent declining yellow-tipped main prickles on the angles, reaching to about the width of the stem, and shorter ones mixed with numerous acicles and pricklets on the faces. Short-stalked glands may be sparse or numerous, but many of the acicles and pricklets are also gland-tipped. Hairs are always present but may be fairly sparse or scattered. The overall appearance is a typical Hystrican armature with various sized glands and prickles, but almost glabrous. The stem may be slightly pruinose.
