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.
Basals.
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.
Involucre.
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.
At first glance the large sterile
disk flowers appear to be ligules, but a quick second look will prove
otherwise. The plant grows tall and gets very thin and open, much like in the
large picture above.
Photographs taken at Logan Creek, Reynolds County, MO., 6-20-03.
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