Is Merla's knapweed the same as ours in Britain - Centaurea scabiosa or C. nigra (also known as Hardheads ?
Names are confusing.
Spotted knpweed is Centaurea maculosa
"Hardhead" is sometimes used as common name for C. macrocephalea, one of my favorite garden flowers. well behaved tho it has thugish cousins.
I have it occasionally in a rough lawn on an old cinder patch but don't find it at all invasive (it can easily be mown out). It is, indeed, attractive and valuable as the major food-plant of cinnabar moth larvae ('football jersey' caterpillars).
Tansy ragwort Senecio spp. is the host for cinnabar moth, at least over here.
not to be confused with common tansy Tanacetum vulgare
Dave Robison
