Photographer: Rob Routledge Affiliation: Sault College Source: Bugwood.org Copyright: (CC BY 3.0)
Blueweed (Echium vulgare) is a large plant capable of growing up to 3 feet tall with tap roots that extend 12 to 32 inches below the soil. Bluweed flowers from May to September with conical, dark blue flowers, that are 1.5 cm long. The leaves are green, long, thin, have a single mid-vein, and spines along the ventral side of the vein. Stems of blueweed are covered with clear spines from pubescence. It is possible for the stems to have purple spots at the base of the spines.
Blueweed is an aggressive plant that is capable of spreading through an entire pasture within a year. The presence of small thorns covering the plant are harmful to livestock leading to liver damage when ingested, and can cause dermatitis in people. It is recommended to avoid touching blueweed because of the painful thorns similar to a cactus. Blueweed is also a known host of crop-damaging pathogens. Growth and sale of blueweed is prohibited in Washington, Montana, and Wyoming because it has been declared a noxious weed.
Blueweed produces 500 to 2,000 seeds per plant facilitating rapid spread through pastures and rangelands. Seeds are released from the plant and fall to the ground near the parent. Spreading is facilitated by attaching to fur, feathers, or clothing. Seeds are capable of remaining viable in the ground for several years.
Traditionally, the leaves of blueweed were boiled into tea and used as a headache remedy due to the alkaloid content. Blueweed was also introduced as an oil seed crop because of the gamma linoleic acid content of the plant.
U.S. Habitat: As a habitat generalist capable of surviving with little water, blueweed is found in a variety of areas throughout the U.S. such as waste ground, roadsides, gravel bars, and sand bars.
U.S. Present: Blueweed is found in 42 states within the U.S. -- click to view range map provided by the USDA
The only management methods for blueweed control are mechanical through pulling or cutting of the plant and herbicide treatment. Mechanical methods require regular cutting or pulling to ensure seed production is reduced eventually damaging the plant to the point of root reserve depletion. Spring or early Autumn applications of herbicide containing 2,4-D has been proven effective in managing blueweed populations. Before applying herbicides read the label for directions of use and all precautions.
BC Ministry of Agriculture and Fisheries. 1988. Blueweed. Agdex 640 Fact Sheet.
Correll, D. S. & M. C. Johnston. 1970. Manual of the vascular plants of Texas. (F Tex)
El-Shazly, A., T. Sarg, A. Ateya, A. Abdel Aziz, and S. El-Dahmy. 1996. Pyrrolizidine Alkaloids from Echium setosum and Echium vulgare. Journal of Natural Products 59(3): 310-313.
Klinkhamer, Peter G. L., and Tom J. de Jong. 1990. Effects of Plant Size, Plant Density and Sex Differential Nectar Reward on Pollinator Visitation in the Protandrous Echium vulgare (Boraginaceae). Oikos 57(3): 399-405.