Artemisia longifolia is North American species in the daisy family, known by the common name long-leaved sage or longleaf wormwood.

It is native to western Canada (Manitoba, Saskatchewan, Alberta, British Columbia) and the north-central United States (Montana, the Dakotas, Minnesota, Wyoming, and Colorado with a few isolated populations in Oklahoma).

Leaves are longer and narrower than for most related species, up to 12 cm (5 inches) long.

The species grows in barren areas, in grasslands, and in alkaline flats in the high plains.

It is relatively well behaved in the garden, not seeding as freely as some other Artemisia species and only being somewhat rhizomatous.