Look out for prickly Paterson's Curse in wildflower seed mixes

Look out for prickly Paterson's Curse in wildflower seed mixes
Last Updated: 
July 1, 2008

CORVALLIS, Ore. – The prickly, blue-flowered plant, called Paterson's curse, (Echium plantagineum), is native to Mediterranean Europe and North Africa. In other areas of the world, including Australia, Paterson's curse has become a well-established noxious weed, where it excludes beneficial forage species and degrades the quality of pastureland.

An estimated 82 million acres in Australia are infested with this weed, costing landowners approximately $250 million annually. This weed degrades pastures and increases the need for land management and its prickly seeds contaminate wool.

Since 2003, Paterson's curse has been found in two locations in Oregon. The Oregon State University Extension Service's new weed specialist, Andy Hulting, wants gardeners and landowners to be on the lookout for this prickly, but beautiful plant.

Echium plantagineum, or Paterson's curse is also known as Salvation Jane, Riverina bluebell, Lady Campbell weed, purple viper’s bugloss or viper’s bugloss. Whatever you call it, it is in the borage family, a relative of forget-me-nots, fiddleneck and the herb borage.

First documented in Linn County as a roadside infestation in 2003, scientists concluded that the seeds were introduced as part of a wildflower seed mix. The weed currently covers an area of less than one acre at that location and is being managed by hand pulling and spot applications of herbicide.

In 2004, a larger site was documented in Douglas County, where it covers approximately 100 acres and is being managed with herbicides, said Hulting. There are no documented infestations in Washington or Idaho, but populations do exist along the central and southern coast of California and in several eastern states.

Outside of its native habitat, Paterson's curse is an aggressive, drought-tolerant plant that adapts to different soil moisture levels, enabling it to readily inhabit disturbed areas. It is purportedly named after an Australian family, the Patersons, who planted it in their garden in the 1880s and watched helplessly as it took over the landscape.

"Pasture lands and oak savanna habitat in western Oregon are particularly vulnerable to invasion, as they are similar to the native habitat of Paterson's curse and may provide an excellent environment for this species," said Hulting. "This weed has the potential to severely degrade agricultural and native habitats but can still be contained and eradicated in the Pacific Northwest because of its limited distribution."

Part of the problem for Oregon is that this species is sold in wildflower mixes, those mixtures of seeds sold by seed companies around the country. This is the most likely way this noxious weed will be introduced to new areas in Oregon, said Hulting. There may also be interest in some areas of the country in growing it to be harvested as an oil seed.

Hulting says the most important thing property owners can do to prevent infestations is to read the list of species in a wildflower mix before buying it or planting it. Do not plant mixes that contain known exotic and/or invasive species, warned Hulting.

Next most important is learn to identify it. Hulting and his colleagues have published an OSU Extension Service online guide to Paterson's curse, complete with photos.

Paterson's curse is an erect winter annual or biennial; seeds usually germinate in early autumn, but can germinate throughout the year when environmental conditions are favorable. Blooming generally starts in June in Oregon, but flowering plants can be found throughout the year. It should not be confused with another weedy species, Echium vulgare, most commonly known as blueweed, but also known as viper's bugloss in some parts of the United States.

The flowers of Paterson's curse have five petals, are trumpet-shaped, and are approximately one inch long. They are most commonly bluish-purple, but can be pink or white. Flowers are borne at the tip of each fiddleneck-like inflorescence. Two of the five stamens protrude significantly from the corolla. In contrast, all five stamens of blueweed, the species commonly confused with Paterson's curse, protrude from the corolla.

Each flower produces four brown or gray "nutlet" seeds, which are surrounded by a bristly husk. An Australian report states that an individual plant can produce up to 10,000 seeds, although seed production decreases to 15 to 250 seeds per plant where grazing occurs. Data from the same report suggest that seeds recovered from the soil seedbank were still viable after 11 years.

Paterson's curse reproduces and spreads via seeds. The seeds are spread to new locations mainly by contaminated wool and fur, hay, equipment, and seed, including wild bird feed and wildflower seed mixes. Paterson's curse can also be transported via runoff water. Transport by wind is unlikely because the seeds are heavy and are not wind-borne.

Similar to other invasive species, Paterson's curse seems to thrive in disturbed environments outside its native range. Paterson's curse has a deep taproot, which allows it to take advantage of soil moisture that other species cannot reach.

In Oregon, Hulting recommends prevention, aggressive containment, and eradication of established populations since Paterson's curse does not infest extensive acreage.

"It is imperative to be attentive to possible new introductions of Paterson's curse," said Hulting. "Seeds can be introduced on vehicle tires, soil, livestock, wild bird feed, and wildflower seed mixes. When moving vehicles or equipment from one field to another, especially if invasive weeds are present, it is important to clean farm equipment, vehicles, boots, and any surface that could spread seed.

“It is also crucial to communicate with neighboring property owners and other concerned groups and individuals about potential new populations of Paterson's curse."

Paterson's curse is spread only by seed, so if you pull the plant before it set seed, you can eradicate it. It is important to revisit these infested sites, especially in the spring, to ensure that seedlings are removed before flowering.

If you suspect a new introduction of Paterson's curse or other invasive weed, contact your local county office of the OSU Extension Service or Oregon Department of Agriculture. Or submit a sighting online at weedmapper.org or call 1-866-INVADER.

Author: Carol Savonen
Source: Andy Hulting