27. Rubus missouricus L.H. Bailey

Pl. 543 c, d; Map 2525

Canes 80–170 cm long and 70–150 cm tall, 5–7 mm in diameter, erect to arching the first year, arching the second year; clonal by root-suckering but not tip-rooting. Prickles moderate to dense, 1–5(–8) per cm of cane, 2–5 mm long, needlelike, straight or somewhat downward angled. Petioles with soft, nonglandular hairs, armed with downward-angled or downward-curved, needlelike prickles to 3.5 mm long. Stipules 15–20 mm long, lanceolate, basal to somewhat lateral, diverging 0–3 mm from the base of the petiole. Primocane leaves with 3 or 5 leaflets, the margins sharply and somewhat irregularly toothed, the upper surface thinly hairy, the undersurface velvety hairy. Central primocane leaflets 7–10 cm long and 4.0–5.5 cm wide, elliptic to obovate-elliptic, rounded to angled at the base, tapered to a sharply pointed tip, the leaflet stalk about 1/5–1/3 as long as the leaflet blade; lateral primocane leaflets elliptic to obovate-elliptic, often asymmetrically lobed when only 3 leaflets are present, angled at the base, tapered to a sharply pointed tip, stalked (the stalks much shorter in the basal pair). Inflorescences varying on a single cane from large, compound, flaring inflorescences, almost broomlike in appearance, to reduced, simple racemes, 8–21(–35) cm long and 6.5–15.0 cm wide, with 7–20 flowers and 2–5 bracts, mostly with 3 leaflets; flower and inflorescence stalks with dense nonglandular hairs, rarely with a few hairlike prickles. Sepals 5–7 mm long, 2.5–4.0 mm wide, ovate-elliptic to triangular, tapered abruptly to a short, slender point. Petals 10–14 mm long, obovate, typically white, but sometimes drying to a light rose pink. Fruits 10–20 mm long and 12–17(–19) mm wide, globose to short cylindric or short-conic. 2n=21, 28. May–June.

Uncommon, mostly north of the Missouri River (north-central U.S. from Missouri north to Minnesota and east to Michigan). Upland prairies, bottomland prairies, edges of bottomland forests, and banks of streams; also pastures and fencerows.

Rubus missouricus was described by L. H. Bailey (1932) from Missouri, with the type material collected by B. F. Bush from Jackson County. It was considered endemic to Missouri, even in Steyermark’s (1963) treatment. The species has not often been collected in the state and most of the specimens in herbaria are historical. The species typically begins to flower a week or two later than neighboring populations of other native members of subgenus Rubus.