Rubus arcticus subsp. acaulis (Michx.) Focke
- En: stemless raspberry, plumboy (NL), dwarf raspberry, stemless arctic bramble, arctic bramble, nagoonberry
- Fr: ronce acaule
Rosaceae (Rose Family)
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General: A perennial dwarf shrub with herbaceous stems, 5–10 cm tall, growing from thin branched rhizomes.
Leaves: 2–3, alternate, compound with 3 leaflets (trifoliate), pinnately-veined, coriaceous, petiolate. Leaflet blades obovate, 1–3.5 cm long; the 2 lateral leaflets sessile, often deeply divided, the terminal leaflet with a short stalk (petiolule); leaflet bases tapering (cuneate); apex pointed (acute) to rounded; margins entire near the base, sharply toothed (serrate) near the apex.
Flowers: Bisexual, solitary. Calyx with 5–8 narrow-triangular lobes, to 1 cm long; petals 5–8, bright pink to reddish-purple, 1–1.5 cm long, obovate; stamens numerous; pistils several. Flowers bloom in mid summer.
Fruit: A deep red to dark purple raspberry (aggregate of drupelets), 1 cm in diameter, edible, very sweet. Fruit matures in late summer.
Habitat and Range: Bogs, wet meadows, peaty depressions, and tundra. Rubus arcticus subsp. acaulis is native to boreal and arctic-alpine regions of North America. In Ontario, it is found as far south as Lake Superior; it is absent from southern and eastern Ontario.
Similar Species: Rubus pubescens (dewberry or dwarf raspberry), has a more southern distribution than Rubus arcticus subsp. acaulis. Rubus pubescens has thin leaves with a diamond-shaped (rhombic) terminal leaflet, widest at the centre and tapering in both directions to a pointed (acute) base and apex; its flowers have white to pale pink petals. Rubus pubescens is a good indicator of rich forest sites; it sometimes hybridizes with Rubus arcticus subsp. acaulis where their range overlaps.