Rubus violaceifrons

Rubus violaceifrons is a tetraploid species of bramble in the subgenus Rubus. It has densely haired leaves and white flowers with bright red-purple styles. The canes are purple-spotted in the shade and brown-red in sunny areas. It is possibly endemic to Bohemia, where it grows in forest margins and clearings.

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DESCRIPTION: — Shrub 30 – 100 cm tall. Primocane stems low to medium high arching, relatively thin, (4 –) 5 – 6.5 (– 8) mm in diameter, angled, with flat or slightly furrowed sides, greyish light green (sometimes whitish or purplish pruinous) and sometimes dark purplish spotted in shaded places or intensively suffused with brown-red in sunlit sites, with ca. 50 mainly simple hairs per 1 cm of stem side and with numerous somewhat unequal violet (or olive green and reddish when shaded) stalked glands up to 2 mm long; prickles numerous, (9 –) 11 – 20 (– 28) per 5 cm of stem length, almost equal, quite slender, straight to only very slightly curved, slightly declining, with a slightly compressed base, glabrous or sparsely hairy at the base, suffused red, with a yellowish tip, (2 –) 2.5 – 4 (– 4.5) mm long, with a (2.0 –) 2.3 – 3.3 (– 3.7) mm wide base. Primocane leaves pedate, (3 –) 4 – 5 - foliolate (when 3 - foliolate then with basal lobes on lateral leaflets), leaflets usually not contiguous, almost flat, quite stiff, leathery and shiny, deep green, glabrous or with few hairs (near margins), and often with innumerable small sessile glands above, yellowish-green or only slightly greyish beneath, with simple or sometimes also with scattered tufted (mainly on veins) hairs, distinctly hairy to the touch; terminal leaflet with midlong petiolule (petiolule length 25 – 35 % of leaflet lamina length), usually obovate, broadly obovate to suborbicular, most often slightly cordate at the base, with an almost gradually acuminate apex (5 –) 12 – 17 (– 19) mm long, with an almost flat, indistinctly double (periodically) serrate margin, principal teeth apiculate (sometimes with a retrorse apex), usually broader than long, with incisions 1.5 – 2 (– 3) mm long; lateral leaves slightly smaller than the terminal one, basal leaflets distinctly smaller, with petiolules 2 – 4 (– 6) mm long; petioles usually longer than the basal leaflets, 5 – 7.5 (– 9) cm long, densely hairy, with numerous stalked glands and with (5 –) 10 – 15 (– 20) straight or slightly curved, slightly declining prickles, round or only shallowly canaliculated at the base; stipules narrowly lanceolate. Inflorescence conical, usually short, distal 3 – 5 (– 8) cm long part leafless. Inflorescence leaves predominantly ternate (the uppermost 1 – 2 leaves simple), with scattered adpressed simple hairs and shortly stalked glands above, with numerous simple and tufted (and rarely stellate) hairs beneath; axis slightly flexuous, densely hairy, with numerous stalked glands and with 5 – 7 prickles on 5 cm axis length, prickles almost straight, slightly declining, 2 – 4 mm long, inflorescence branches pointing obliquely upwards or patent; pedicels (4 –) 6 – 12 (– 18) mm long, densely hairy, mainly with adpressed tufted hairs, with numerous stalked glands and with 0 – 2 (– 4) acicular prickles 1 – 2 mm long. Flowers mid-sized, (1.7 –) 2.1 – 2.3 cm in diameter; sepals long pointed, 6 – 7 mm in length (including appendix), often with a lanceolate appendix (1.7 –) 2.2. – 2.7 (– 3.2) mm long, usually reflexed after anthesis, on the back greyish, tomentose, with a white felted margin, and with numerous dark red stalked glands which are a little shorter than protruding simple hairs, sometimes also with whitish pricklets; petals white, obovate elliptical, emarginate, not contiguous, (9.0 –) 9.2 – 9.6 (– 10.4) mm long, (4.7 –) 5.3 – 5.7 (– 6.1) mm wide; stamens longer than styles, filaments white, anthers glabrous; carpels with tufted to stellate (rarely simple) hairs or glabrescent, styles distinctly dark red-violet; receptacle glabrous or with few short hairs. Collective fruit mostly well developed, subglobose, (0.7 –) 0.9 – 1.2 (– 1.4) cm long, 1.1 – 1.3 cm wide, blackish and shiny when mature, with small, numerous, (16 –) 20 – 34 (– 49) drupelets.