Gina Darin. Acroptilon repens, a dicot, is a perennial herb that is not native to California; it was introduced from elsewhere and naturalized in the wild. Acroptilon repens (Linnaeus) de Candolle in A. P. de Candolle and ; Acroptilon picris (Pallas ex Willdenow) C. A. Meyer; C. picris Pallas ex Willdenow. Acroptilon repens. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences.

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Journal of Neuroscience Research. Nevada Centaurea repens Russian knapweed Noxious weed. Acroptilon repens is poisonous to horses and can cause a neurological disorder called “chewing disease”.

Plants Profile for Acroptilon repens (hardheads)

It reproduces vigorously from seed and spreads from adventitious buds borne on deep-seated runner roots. Selected Weeds of the United States. Vector Transmission Birds and rodents eat the seeds of R. US Fish and Wildlife Service, b.

Disciform heads superficially resemble discoid heads, with pistillate or sterile flowers that lack rays, together with or separate from disk flowers.

Acroptilon repens, Russian Knapweed – eXtension

The rosette leaves can be unlobed to very lobed and are 2 to 4 in. It is characterized by its extensive root system, low seed production, and persistence. Centaurea picris Pallas ex Willd. IPM Practitioner, 24 4: Accidental introductions of R. Because of its bitter taste, it is usually avoided by grazing animals, and consequently it tends to spread when more palatable plants are consumed.


It is very difficult to control or eradicate once it becomes established.

The species was first described by Carl Linnaeus in as Centaurea repens. Discussion View source History. Involucres mm, loosely cobwebby. Seeds germinate over a wide range of temperatures, from 0.

Northwest Science, 69 2: Picloram does not bind to soil and may leach into groundwater. Randall, The Nature Conservancy, bugwood. Russian knapweed invades disturbed grassland and shrubland communities, as well as riparian forests. The rust fungus Puccinia acroptili acroptulon, which was accidentally introduced into North America Canada before is widespread, but it does not control R. A disk flower has a generally radial corolla, with a cylindric tube, expanded throat, and generally 5 lobes.

Journal of Range Management, 52 4: The microscopic nematode is worm-like and about 1. Content is available for non-profit, educational use under our Copyright Agreement.

Upper leaves are entire, cm long, linear to narrowly oblong with a sharp-pointed tip. Detection and Inspection Top of page Monitoring is also important for control of R.


Rhaponticum repens

Acroptilon repens does not appear to reproduce extensively fepens seed but just one plant may produce 1, seeds per year. If not applied carefully, it can damage or kill other broad-leaved, non-target plants, particularly other composites, legumes or smartweeds.

United States Department of Agriculture, If these agents are already present in your state, but not on your site, you can collect and transport them within the state without a permit from the USDA. Galls can be collected in the fall and placed upon the soil to permit the nematode larvae to emerge from the wet, disintegrating galls and penetrate the young knapweed shoots when they break through the soil in the spring.