Rubus cantabrigiensis – Section Corylifolii

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This bramble was described relatively recently by Alec Bull and Alan Leslie (Watsonia 25, 2005: 419-422). It had been collected by the authors in recent times, dating back to 1973, but herbarium searches of undetermined Corylifolians found that it had also been collected as far back as the late 1880s. It is locally abundant and characteristic of calcareous boulder clay soils in East Anglia and Cambridgeshire, after which it was named, and is also recorded from Essex, Hertforshire and Kent. It typically grows in open situations, forming clumps around 1-1.25m tall. The photos here are mostly from a single colony seen at Steps Hill, Buckinghamshire, during a BSBI bramble meeting in 2023. It is a typical Corylifolian (with pleated leaflets, patent prickles and round petals) but is relatively distinctive due to its pink petals, red-based styles and dull, grey-green leaflets.

Below: panicle showing congested head of flowers and straight rachis armed with rather long, straight prickles (photo © A. Biddle).

Flowers are c.2.5 cm in diameter. Petals are sometime white but usually pale to mid-pink, broadly elliptical, 13 x 10mm in this specimen (published range 10-12 x 6-8mm), often notched, and unusually for Corylifolians, not contiguous. The stamens are relatively long and dense in appearance. Styles may be red-based or wholly red. Anthers, carpels and receptacle are glabrous. Sepals are felted with some reddish glands and acicles visible mainly near the apex; reflexed, becoming patent to loosely clasping as the fruit develops.

Below: flower showing long stamens and red-based styles (photo © A. Biddle).

Leaves have (3)-5 leaflets with the basal pair almost sessile and partly overlapping. They are rather matt grey-green above, moderately rugose (probably more pronounced when growing in the open, as here). The margins are finely and sharply serrate, undulate. The terminal leaflet is broadly elliptical-obovate, c.6-8 x 5-7 cm, with a relatively short but well defined cuspidate or acuminate apex and an emarginate base. Some have straight sides below the widest point.

Below: photos © A. Biddle.

Leaflets are whitish-green feltd below.

The non-flowering first year stem is glaucous green becoming a dull reddish-brown, bearing frequent strong, broad-based prickles of similar colour to the stem with a yellow tip which is often upturned. The prickles are mainly confined to the angles. Stems appear virtually glabrous, but on close inspection may have some sparse hairs and scattered small glands and acicles.