13. Rubus aboriginum Rydb.

R. mundus L.H. Bailey

Map 2511

Canes to 350 cm long and 40 cm tall, 2.5–5.0 mm in diameter. Prickles usually moderate, rarely dense, 1–3(–6) per cm of cane, 1.5–3.0 mm long (but cultivated selections exist that lack cane prickles). Petioles with sparse to dense nonglandular hairs, armed with downward-curved to downward-angled prickles to 2 mm long. Stipules 12–21 mm long, linear to lanceolate. Primocane leaflets 3, 5, or rarely 7, the margins irregularly jagged, often doubly toothed, the upper surface thinly hairy, the undersurface velvety hairy. Central primocane leaflets (5.5–)6.0–9.5 cm long and (4.0–)4.5–7.0(–7.5) cm wide, ovate to elliptic or elliptic-obovate, subcordate to rounded at the base, tapered to a sharply pointed tip, the leaflet stalk extremely variable in length relative to the leaflet blade; middle leaflets ovate to elliptic or rhombic, rounded to angled at the base, angled to tapered to a sharply pointed tip, stalked; basal leaflets ovate to elliptic, angled at the base, angled to a sharply pointed tip, nearly sessile, often asymmetrically lobed when only 3 leaflets are present. Inflorescences 3–15(–22) cm long, with 1–5 flowers on long, ascending stalks and 1–6 leafy bracts, these mostly with 3 leaflets; flower and inflorescence stalks with nonglandular hairs and sometimes with needlelike prickles. Sepals 6–8 mm long, 3–4 mm wide, triangular, often with a prominent spatulate tip 1–3 mm long. Petals 10–22 mm long, broadly obovate. Fruits 10–30 mm long, 12–20 mm wide, subglobose to cylindric. 2n=56. April–June.

Scattered, mostly south of the Missouri River (southeastern U.S. west to Kansas, Oklahoma and Texas). Bottomland forests, mesic upland forests, swamps, banks of streams and rivers, bottomland prairies, upland prairies, and fens; also old fields, fallow fields, fencerows, railroads, and roadsides.

Large-fruited and unarmed selections of R. aboriginum have been cultivated and may escape or persist from gardens. In addition to rooting at the tips, the canes of this species sometimes also root at the nodes, an unusual character in the section. Another unusual character is the presence of extra petals. A collection of R. aboriginum with 10 petals was made by J. Pinkston in Macon County in 1997 and is accessioned at the herbarium of Missouri State University.