Rubus titanus Bailey (1925: 222)

Beek, Abraham Van De, 2021, Rubi Capenses: a further contribution to the knowledge of the genus Rubus (Rosaceae) in South Africa, Phytotaxa 515 (1), pp. 1-71 : 43-44

19. Rubus titanus Bailey (1925: 222) .

Type:—to be designated (James Reveal selected types for the taxa that Bailey described from the Bailey herbarium, but he died before he could publish these. The publication is left to Mark Widrlechner, as also for other American species that Bailey described)

Primocane ( Figs 16A–D ) low arching to prostrate, roundish to angular, diam. 4–8 mm, with scattered to rather numerous long patent hairs and some (sub-)sessile glands; prickles 20–100 per 5 cm, unequal, subulate or compressed, up to 5–7 mm long, straight or slightly declining; stipules linear ovate-lanceolate, 8–18 mm long, hairy, with some short stipitate glands. Leaves 3(–5)-foliolate, adaxially with appressed hairs or almost glabrous, abaxially green, pubescent, not to clearly soft on the touch; serrature coarse, deep periodical, with straight triangular teeth; petiole 3–8 cm, with some patent hairs and subsessile glands, and 10–50 unequal up to 3–5 mm long subulate or acicular, patent or declining prickles; central leaflet ( Fig. 16E ) of 3-foliolate leaves 66–122 mm long, ovate or rhombic-obovate, with an emarginate or cordate base, gradually attenuate, acute to moderately acuminate, sometimes lobate, width–length index 0.51–0.93, length of petiolule 14–37% of length of leaflet; petiolule of lateral leaflets 0–3 mm. Flowering branch ( Fig. 16F ) angular, with some to rather numerous long hairs and usually some subsessile glands; prickles 4–10 per 5 cm, unequal, acicular or slightly compressed up to 4–6 mm long. Inflorescence ( Figs 16G–H ) with large leaves to apex; peduncles ascendant, much shorter than leaves; pedicels 10–45 mm long, with long hairs, eglandular or with some subsessile glands, and some pricklets. Flowers: sepals green or slightly greyish green, with long hairs and without glands or prickles, patent or loosely reflexed; petals ( Fig. 16I ) white, large ovate, 16–20 mm long, 11–14 mm wide, width–length index 0.60–0.87; stamens much shorter than styles; anthers glabrous; ovaries with some hairs, soon becoming glabrous; receptacle hairy. Mature fruit black.

Ecology: —Ruderal hedges.

Distribution in South Africa: — Western Cape: Contantia Neck, Stellenbosch, Betty’s Bay.

Specimens:— SOUTH AFRICA. Western Cape: Road from Kirstenbos to Houtbaai, west of the road to Alphen, 12 October 2018, Beek 2018.87 ( L) ; Along vineyard left of the road to Delheim, Stellenbosch, 16 October 2019, Beek 2019.88 ( L) ; Stellenbosch, Jonkershoekweg, near houses rather short before the entrance gate of the park, 14 October 2018, Beek 2018.93 ( L) ; Betty’s Bay , Harold Porter Botanical Garden, SE corner, just south of the wooden stage, 24 February 2018, Beek 2018.13 ( L) ; Betty’s Bay , SW corner of Harold Porter Botanical Garden, 9 October 2018, Beek 2018.84 ( L) .

Note: — Rubus titanus is a fertile artificial hybrid, which is cultivated for its fruit (Mammoth Blackberry, Bailey 1925). It often escapes to natural habitats where it behaves as a normal species. Consequently Bailey described it as such. The plants in South Africa are assumed to have escaped from berry orchards.

Figures

FIGURE 16. Rubus titanus. A. Habit. B. Primocanes and leaves. C. Primocane. D. Primocane. E. Leaflet. F. Flowering branch. G. Inflorescence. H. Inflorescence. I. Flower. Photographs: A. van de Beek.