Photo of viper’s bugloss, closeup of flower
Rob Routledge, Sault College,
Other Common Name
Blueweed; Blue Devil; Blue Thistle

Boraginaceae (borages)


Viper’s bugloss is a biennial plant with bristly hairs and usually with single stems. Flowers along upper stalks in one-sided spikes in an unfurling, tight coil; funnel-shaped with uneven lobes to ¾ inch long; pink in bud, blue to ultramarine later, with pink stamens protruding. A form with white flowers occurs rarely. Blooms May–September. Leaves linear-oblong, sessile, extremely white-hairy (as are the stems), giving the plant a silvery appearance.


Height: 1 to 2½ feet.


Photo of viper’s bugloss flower cluster
Viper’s Bugloss (Blueweed; Blue Devil; Blue Thistle)

Viper039s Bugloss-20190609-2121.jpeg

A plant with a spiky stem and leaves has multiple purple flowers with long stamens. A bee is in one of the flowers.
A bee pokes its head into a Viper's Bugloss at Johnson Shut-Ins State Park
Habitat and conservation

Native to Europe. Occurs in moist or dry places, including banks of streams or rivers, gravel bars, upland prairies, openings of moist upland forests, pastures, railroads, roadsides, and open, disturbed areas.

image of Viper’s Bugloss Blueweed Blue Devil Blue Thistle Distribution Map
Distribution in Missouri

Scattered mostly in the eastern half of the Ozarks and Ozark Border Divisions of north, eastern, and central Missouri.


“Bugloss” is a common name for borages in Europe. The plant is associated with “vipers” because the nutlets supposedly resemble a snake’s head. According to antique medicinal reasoning, that resemblance signified that the plant could function as a treatment for snakebites. Since the plant contains toxic alkaloids, eating it could poison you.

Human connections

This plant, like many other members of the borage family, contains toxic alkaloids that make it a potential problem for livestock that graze on it, which might happen if this plant spreads to an overgrazed pasture from a nearby roadside.

Ecosystem connections

Bees, butterflies, skippers, and other insects are attracted to the pollen of viper’s bugloss. With its toxic chemicals, it is unlikely that many mammals eat it. If caterpillars (immature butterflies and moths) eat it, there is a good chance they become toxic, thus protected from their predators.