Collinsonia canadensis

Richweed/Stoneroot Lamiaceae

A member of the mint family with a name that sounds like a Victorian apothecary and flowers that smell as though someone has sneaked a citronella candle into the woodland. Collinsonia canadensis produces handsome, sharply toothed leaves beneath branching sprays of tiny, pale-yellow flowers in late summer, making it a useful choice for the shady border where the floral fireworks are usually running out of steam. In the wild it inhabits rich, often rocky woodland, ravines and wooded slopes across eastern North America, from southern Ontario through the eastern and south-central United States, extending south to Florida and Alabama. Its ethnobotanical history is every bit as interesting as its flowers: Indigenous peoples used the plant medicinally, and its tough, dense roots and rhizomes later became valued in traditional North American herbalism, earning it the common name ‘stoneroot’. The foliage has also been used to make herbal tea. Give it humus-rich, moisture-retentive soil in partial shade, ideally with room to form a substantial clump. Not a show-off, perhaps, but a fragrant woodland perennial with a rather impressive back catalogue.

• Hardiness: H6 (−20 to −15°C)
• Height: 60–120 cm
• Spread: 30–90 cm
• Flowers: August–September