hazel-leaved, and this widespread and common species has strongly rugose (textured) leaflets, which do resemble the leaves of Hazel. It has large flowers with white, rounded petals and stems bearing numerous prickles of varying sizes and abundant stalked glands, indicating that it probably derived from one of the Hystrices. It is one of the first brambles to start flowering (as early as May in the south of England) and is tolerant of warm, sunny sites (e.g. in coastal areas), but also frequently grows in shade.
Like most Corylifolii the inflorescences tend to be composed of tight clusters of relatively few flowers.
Flowers are about 3.5cm across, larger than most other white-flowered Corylifolians. The petals can be up to about 17mm long and are broadly elliptical to almost round. The stamens are distinctly longer than the green styles and the anthers seem to darken more so than in other species after the pollen is shed, giving the flowers a distinctive look. Note that when the flowers are fully open the petals are not touching – they usually touch in most other Corylifolii. The carpels are hairy.
The panicle leaves are single or tri-foliate, usually convex, rugose and often obovate (wider above the middle). The rachis has long, fine prickles and unlike the stem is quite hairy.
This plant was photographed on Borth Bog in mid Wales.
Flower on a plant growing in shade.
After flowering the tips of the sepals curl upwards and may become erect, but this is typical of many Corylifolii. Also in common with many others in the section, the fruits are often small or imperfectly formed.
Leaves are nearly always strongly rugose in sun or shade, often convex and characteristically dull greyish-green in colour, except when young when they may be more yellowish-green. Leaves may have 5 leaflets or 3 with one or both the basal leaflets budding off from the laterals and sometimes one of these fully developed. The relatively large terminal leaflet is about 9-10cm long, obovate and generally has a short, cuspidate apex.
Below is a leaf from a plant in semi-shade showing typical colour and less rugose texture, even though the veins are strongly marked. On 5-foliate leaves such as this the two basal leaves arise from the stalk of the lateral leaflets, i.e. they are
pedate rather than
digitate (where all the leaves arise from the same point on the petiole). However, because the basal leaflets are sessile, this is difficult to see.
Leaflets are shortly downy below and are generally yellowish- or greyish-green. The first photo below is a less rugose shade leaf.
The dense prickles and pricklets on the stem are a distinctive feature, though like all brambles they vary somewhat depending on the age of the stem and its situation – compare the photos below. This species often sends out very robust and strongly armed runner stems. The purplish colour only develops in the sun. The prickles are generally patent or slightly declining. There are numerous stalked glands and sometimes sparse hairs, but often the stems are glabrous and shiny. They may also have patches of a white waxy coating. Stems in shade are less prickly.
Young stems in sun:
Older stems in sun:
The presence of prickles which are distinctly longer than most of the others helps distinguish this species from Rubus intensior which has prickles more equally variable in length. Rubus intensior can look rather similar to R. tuberculatus, but has smaller flowers and less rugose, flatter, mid-green leaves (which may possibly have a longer apex). The stem is described as bright red in colour rather than the purplish-red of tuberculatus evident in the photos above. It has glabrous or nearly glabrous carpels.