24. Rubus armeniacus Focke (Himalayan blackberry)

R. discolor Weihe & Nees

R. procerus P.J. Muell., misapplied

Pl. 542 a–c; Map 2522

Canes to 350 cm long and 100–300 cm tall, 5–15 mm in diameter, often branched. Canes with sparse tufted or simple hairs, becoming nearly glabrous at maturity. Prickles moderate, 0.6–1.4 per cm of cane, 8–11 mm long, often with red at or near their bases. Petioles with nonglandular hairs, armed with many broad-based, downward-curved prickles to 5 mm long. Stipules 10–12 mm long, linear to filiform, clearly lateral, diverging 3–6+ mm from the base of the petiole. Primocane leaves with (3)5 leaflets, margins irregularly, coarsely, and sharply toothed, the upper surface nearly glabrous, the undersurface white- to light gray-felted, the midvein on the undersurface drying to a light yellow. Central primocane leaflets 5.0–12.5 cm long and 6.0–9.5 cm wide, suborbicular to broadly elliptic-obovate or oblong-obovate, cordate to rounded at the base, abruptly short-tapered to a sharply pointed tip, the leaflet stalk about 1/3–2/5 as long as the leaflet blade; lateral primocane leaflets resembling the central leaflet but somewhat smaller, the basal pair with stalks 3–6 mm long. Inflorescences typically paniculate, 28–38 cm long and 8–18 cm wide, with 5–31 flowers and 3–7 leafy bracts, these concentrated at the basal nodes, a mixture of simple bracts, and those with 3 and 5 leaflets; flower and inflorescence stalks with dense nonglandular hairs, and strong straight to downward-angled prickles; the flower stalks sometimes with a few gland-tipped hairs and lanceolate, stipulelike bractlets to 15 mm long, the lower inflorescence stalks covered with tufted clusters of hairs (sometimes appearing stellate-hairy). Sepals 3.0–3.5 mm long, 6–8 mm wide, triangular, abruptly tapered to a sharp tip. Petals 13–20 mm long, broadly elliptic, pale pink. Fruits 10–20 mm long, 10–20 mm wide, oblong. 2n=28. May–June.

Introduced, scattered in the southern portion of the Ozark Division (likely native to the Caucasus; naturalized widely in Europe, U.S., and adjacent Canada). Banks of streams, also pastures and roadsides.

This species is likely represented in Missouri only by escaped or persisting populations of cv. ‘Himalaya’ or similar horticultural selections. It is a serious, invasive pest in the Pacific Northwest. It was treated by Steyermark (1963) as R. procerus, a synonym of the Eurasian species, R. praecox Bertol. (Zieliński, 2004).