Flower:

Showy flower heads 2 inches across, single or a few at the top of the stem. Each head consists of set of 10 to 20, blue to violet ray flowers around the outer edge and numerous, shorter purple disk flowers in the center. Ray flowers are sterile, widely spreading, narrowly tubular with 5 slender lobes as long as or longer than the tube. Disk flowers are fertile, erect to ascending, with a column of dark blue-violet tipped stamens and a divided style.

The bracts (phyllaries) surrounding the base of the flower are in several layers, appressed, triangular to egg-shaped, light green with blackish, finely toothed edging. The entire set of phyllaries (involucre) is ¾ to 1 inch long and longer than wide.

Leaves and stems:

Leaves are alternate, green, lance-elliptic, 4 to 12 inches long, toothless or with a few small teeth, rarely lobed. The upper surface is sparsely short hairy, the lower more woolly hairy.

Leaves are stalkless but the leaf base extends down the stem, creating a wing. Stems are erect, single or multiple from the base, hairy and usually unbranched, sometimes few-branched. Colonies may be formed from creeping rhizomes or stolons.

Fruit:

Seeds are elliptic, creamy colored to brown, smooth, 5 to 6 mm long with a tuft of short, light brown hairs at the tip.

Notes:

Perennial Cornflower is a European species popular in the garden trade, and occasionally escapes cultivation. It's certainly a pretty thing, and not likely to be confused with any other species except other garden variety Centaura species. Our chance encounter was in Grand Portage, on a roadside mixed with non-native Hawkweeds and other weeds. We feel this should be eradicated wherever encountered before it gets a chance to further proliferate in the wild. The north shore of Lake Superior is a hotbed for such things and the risk is high for a rhizomatous species that likes gravelly soil to settle in and further degrade this fragile habitat. Perennial Cornflower's native habitat is mountain meadows so is quite at home in cool, rocky places like the north shore. It can be quite vigorous and spreads by seeds as well as vegetatively—a double whammy. Let's not give this one a chance to make its mark.