Citronella horse balm, broadleaf collinsonia, Canadian collinsonia, citronella, hard hack, heal-all, horse balm, horseweed, knob grass, knobroot, ox balm, richweed, stone root.
A perennial that grows to 3 feet in height. Leaves are opposite, large, coarsely toothed, and roughly ovate in shape. Strongly scented lemon-yellow flowers are arranged vertically along opposite branches of the main stem. Plant rises from a thick, woody rhizome.
July to September.
Rich, moist woods.
Herb at flowering; root in fall.
Roots are used as a sedative and antispasmodic, diuretic, astringent, and tonic.