Northern Prairie Wildlife Research Center
Northeast Wetland Flora
Field Office Guide to Plant Species
Old Field Blackberry
Rubus alumnus L.H. Bailey
- Family: Rose (Rosaceae)
- Flowering: May-June
- Field Marks: The distinguishing features of this blackberry are the erect to arching stems
with broad-based prickles and the branches of the inflorescence and leaves with glandular
hairs. The inflorescence is frequently as broad as long.
- Habitat: Old fields, pastures.
- Habit: Stout shrub to 9 feet long.
- Stems: Upright or arching, stout, covered with broad-based prickles.
- Leaves: Alternate; those of the sterile stems with 3-7 leaflets, the leaflets ovate, pointed at the tip, rounded or heart-shaped at the base, coarsely toothed, hairy on the lower surface with glandular hairs, leaf stalk often with curved prickles; those of the flowering stems simple or divided into 3 or 5 leaflets, otherwise similar to the leaves of the sterile stem.
- Flowers: Several in short, flattened racemes usually about as broad as long; each flower up to 2 inches across, on glandular-hairy stalks.
- Sepals: 5, green, attached below to form a cup, ovate to broadly lanceolate.
- Petals: 5, white, free from each other, up to 1 inch long.
- Stamens: Numerous.
- Pistils: Numerous, each with a superior ovary.
- Fruits: Many drupelets in thimble-shaped clusters up to 1 inch long.
- Notes: Gleason and Cronquist consider this species to be the same as R. allegheniensis. The fruits are eaten by a variety of animals, including humans.
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