Tall Thistle

Cirsium altissimum L.

Asteraceae (Aster Family)

▲ young rosette with un-lobed leaf margins, white undersides

▲ young rosette with lobed leaf margins, white undersides

▲ bolting flowering stem, with unlobed leaves

▲ flower bud

▲▼ flowering plants

▲ flower

Tall Thistle: (pp. 106-107, Weeds of the Great Plains—not in Weeds of the Northeast)

·         biennial weed fairly common in southwest Missouri; similar to canada thistle, but no creeping roots; similar to field thistle, but lacks many small leaves below flower heads found on field thistle

·         upper leaf surfaces green, lower surfaces white woolly

·         flower stalks short and leafy; flowers purplish pink, blooming in mid to late summer

·         flower heads innermost bracts have triangular to lanceolate toothed tips

·         leaves have slender, shallow broad teeth or lobes and leaf margins flat, not wavy