Native to the West Indies, and grows from New Jersey to Missouri, south to Florida and Texas. Reaches 3 feet tall and 23 feet wide, with freely branching stems set with pairs of toothed, dark green, 4 inches leaves. From summer until frost, bears broad clusters of fluffy blue flowers that exactly resemble those of floss flower (Ageratum). Vigorous and freely spreading; invasive in fertile soil. Needs regular water but will not thrive in soggy soil in winter. Attracts bees. Late to appear in spring. Selections include 1- to 2 feet-tall 'Album', with pure white flowers; 2 feet 'Cori', bearing exceptionally clear blue blossoms, later blooming than the species; and compact 'Wayside Form', to just 15 inches.