Brook thistle

Cirsium rivulare is an erect perennial herb of the Asteraceae family growing 50-150 cm tall from a stout, shortly rhizomatous rootstock that produces dense leafy basal rosettes. Stems are slender, simple or branched only in the inflorescence, ribbed, sparsely cobwebby-hairy and usually unwinged. Basal and lower stem leaves are large, oblong-lanceolate, 20-50 cm long, pinnatifid to deeply pinnately lobed with weakly to moderately spiny-toothed lobes, deep green and somewhat glossy above and paler and finely hairy beneath; the upper stem leaves are progressively smaller, less divided and clasping the stem with auriculate, weakly spiny bases. The inflorescence consists of two to five (rarely solitary) ovoid, sessile or shortly stalked capitula clustered at the stem apex, each 2-3.5 cm across. Involucral bracts are appressed, dark purple-tinged and only weakly spine-tipped. Florets are all tubular, deep purple-red, conspicuously protruding from the dark involucre. Achenes are oblong, smooth, brown and bear a long pappus of plumose feathery bristles. Native to damp meadows, stream-sides and marshy ground across central and southeastern Europe, flowering in early to midsummer.