Black knapweed

Family: Asteraceae
Scientific name: Centaurea x moncktonii
Description: Plant Form: Upright perennial herb. Size: Usually under 1 m tall. Stem: Ribbed, roughly hairy. Leaves: Alternate on stems up to 8 cm long along main stem, undivided, narrow or widest towards base, weakly toothed, sessile. At base of plant clumped, sometimes lobed, up to 25 cm long. Flowers: Solitary cornflower-like flowerheads with purple florets 15-20 mm long. Brown bracts surround the flower giving a pine-cone like appearance. Fruit and Seeds: 2-3 mm long, pale brown to grey, with reduced parachuting hairs only 1 mm long or missing. Habitat: Roadsides, disturbed sites, pastures. Distinguishing Features: Distinguished from Creeping knapweed (Rhaponticum repens) by having dark brown or black tip on bracts, and Spotted knapweed (Centaurea stoebe subsp. micranthos) by generally having less deeply lobed leaves. Weed Status: Priority Weed Weed Type: Agricultural Lifeform: Herbaceous

Example images for this weed