Centaurea maculosa Lam.
Family - Asteraceae
Stems - To 1.5m tall, erect to reclining with age, herbaceous, branching, multiple from base, from taproot, arachnoid pubescent above, slightly scabrous, striate.
Leaves - Main cauline leaves alternate, deeply pinnatifid, (many lobes divided again), to +/-12cm long, +/-7cm broad. Ultimate divisions mucronate, scabrous, entire, oblong. Leaves in upper portions of stem greatly reduced, mostly undivided, scabrous, typically arachnoid pubescent, mucronate, linear to oblong.
Main cauline leaf.
Inflorescence - Single flower head terminating stem in a loose paniculiform arrangement of the upper 1/2 of stems.
Involucre - To 1.2cm tall(long), 7-8mm in diameter, ovoid to slightly urcreolate in shape. Phyllaries with prickle tips, imbricate, with some arachnoid pubescence, dark brown to black in upper half, green in lower half. Margins pectinate.
Ray flowers - Absent.
Disk flowers - Outermost flowers enlarged, sterile, 5-lobed. Lobes to 8mm long. Innermost flowers 5-lobed, whitish to pinkish, fertile. Lobes to 4mm long. Anthers pinkish-rose, exserted, connate around style, 2-3mm long. Achenes to 3.5mm long, brown to blackish in fruit, ridged, glabrous to sparse pilose. Pappus of short bristles to 2mm long.
Flowering - June - August.
Habitat - Waste ground, rocky ground, roadsides, railroads.
Origin - Native to Europe.
Other info. - This plant
is considered a pest almost every place it grows outside of cultivation.
It is most common in the southern and especially the southwestern portions of Missouri.
Photographs taken at Logan Creek, Reynolds County, MO., 6-20-03.