7. Rubus rosa L.H. Bailey

Map 2505

Canes to 270 cm long and 150–250 cm tall, 5–8 mm in diameter, primocanes with gland-tipped hairs, at least toward the apex. Prickles moderate to dense, 0.3–3.0 per cm of cane, 6–8 mm long. Petioles with sparse to dense nonglandular hairs and often gland-tipped hairs, armed with broad-based, downward-curved prickles to 4 mm long. Stipules 12–20 mm long, linear to lanceolate. Primocane leaflets soft and clothlike, the margins sharply toothed, the upper surface thinly hairy, the undersurface velvety hairy. Central primocane leaflets 9.5–17.0 cm long, 8.5–13.0 cm wide, broadly ovate or suborbicular, cordate to rounded at the base, tapered to a sharply pointed tip, the leaflet stalk about 1/3 as long as the leaflet blade; middle leaflets ovate to oblong, rounded to subcordate at the base, tapered to a sharply pointed tip, stalked; basal leaflets elliptic, angled at the base, tapered to a sharply pointed tip, nearly sessile. Inflorescences mostly racemose, occasionally flaring and with some secondary branching, especially near the base, 5–36 cm long, 6–13 cm wide, with 5–24 flowers and 1–6 bracts, these often leafy and mostly with 3 leaflets; flower and inflorescence stalks with nonglandular hairs, gland-tipped hairs, and variously shaped prickles. Sepals 7–10(–16) mm long, 3–5 mm wide, triangular. Petals 13–18 mm long, obovate to broadly obovate. Fruits 12–20 mm long, 8–16 mm wide, short-cylindric to short-conic. 2n=21, 28. May.

Possibly introduced, uncommon, known thus far only from historical collections from Jackson County (northeastern U.S. and adjacent Canada west to Nebraska and Minnesota). Bottomland forests and bottomland prairies.

Large-fruited selections of R. rosa have been cultivated and may escape or persist from gardens. Few collections of R. rosa have been made in Missouri, and it is not clear whether any of these represent native populations that predate European settlement.