Black Knapweed

Scientific Name: Centaurea nigrescens Willd
Family: Asteraceae

MORPHOLOGY

Growth habit and size: Perennial herbaceous, erect plant, hairy-rough, with a woody taproot. Height ranges from 40-100 cm.

Stem: Erect, striated, branched stems with erect-patent branches.

Leaves: The long lower leaves have an ovate blade, the margin is entire, rarely 1-2 times incised and lobed towards the base, borne on a long petiole dilated at the base. The cauline leaves are smaller, linear and lanceolate, with a rounded-amplexicaul base.

Flowers: The flower heads are pedunculated, solitary or grouped at the branch tips. They have a narrow, ovoid, or globose involucre. The appendage of the involucral bracts is blackish, triangular, with 6-8 short brown fringes per side, as long as they are wide. The bracts are sparse and do not entirely cover the involucre. The flowers are all ligulate, purplish, sometimes the outer ones are radiant. It blooms between May and December.

Fruits and seeds: The fruits are achenes with a concave hilum, sparsely hairy, striated, light gray, the inner ones sometimes with a short pappus.

DISTRIBUTION AND HABITAT

Found throughout Italy except on the islands. In pastures and uncultivated areas, from 0 to 1,600 m.

Photo: Kindly provided by Claudio Farinati