Linaria vulgaris (Scrophulariaceae)

Description
Linaria vulgaris is commonly known as Butter and Eggs or Yellow Toadflax. It has bright yellow and orange snapdragon-like flowers. L. vulgaris is a perennial herb standing approximately 30 to 60 cm tall with leaves 2 to 10 cm long and 1 to 5 cm wide. When not flowering, the stems and leaves may be confused with those of Flax (Linum spp.) and the flower is said to have a wide mouth similar to a toad’s.

Distribution and Habitat
L. vulgaris inhabits most of North America, parts of South America, Europe, Asia, and Australia. Imported from Europe to North America for ornamental and folk-medicine uses, it is now a noxious weed found in disturbed areas throughout the U.S. It is found at 1524-3048 m in Colorado, where it has invaded the high mountain valleys and parks. Once it is established in disturbed areas, L. vulgaris can spread rapidly into adjacent non-disturbed areas.

Adaptations
The flowers of butter and eggs are bright yellow with an orange lower lip, the coloration is thought to attract insects for pollination. This plant is adapted to use disturbed sites for initial propagation.

Ecological Relationships
Bumblebees and halictid bees are the most frequent pollinators of L. vulgaris. Butter and Eggs is now considered to be a noxious weed throughout the U.S. that robs nutrients and water from the natural flora in areas it colonizes

Status and Conservation
L. vulgaris is still dispersing. The most effective method for destroying colonies is to manually pull the plant. Research on control and management of L. vulgaris is ongoing at RMBL, as it could potentially replace native plant species where it invades.

Highlighted RMBL Research
Dr. Becky Irwin and Dr. Jennie Reithel are currently studying this species.

References
Arnold, R. M. 1982. Pollination, Predation and Seed Set in Linaria vulgaris (Scrophulariaceae). American Midland Naturalist 107:360-369.

Beck. K. G. 2009. Biology and Management of the Toadflax. No. 3.144. Colorado State University, Fort Collins, Colorado, USA.

Kartesz, J.T., Linaria vulgaris Mill. Butter and Eggs. United States Department of Agriculture, Natural Resources Conservation Service, unknown location, USA.

Attribution
Many thanks to Alyssa Keith and Dr. Pat Magee of Western State College for this submission, and to Diana Cosand of Chaffey College for her review and additions.