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Yellow flag iris are pretty but highly invasive.

Ten more invasive plants may be banished from Washington as threats to agriculture, forests and wetlands by the state Department of Agriculture

Some of the non-native plants are attractive enough to have been sold at nurseries or as landscaping, but have escaped and are now deemed noxious weeds. The Washington State Noxious Weed Control Board or the Department of Ecology petitioned the agriculture department to ban the plants, including seeds, from being bought or sold. Many of the plants already must be eradicated in some counties.

The department announced the list this month as the first formal step in prohibiting the weeds. State regulations already list 92 banned plants. Trafficking in banned plants can be punished by up to $5,000 per violation.

The plants being considered for banishment are:

• Yellow flag iris grows 2- to 3-feet tall in shallow water. The ornamental plant has been found on both sides of the Cascades and can sicken livestock. Although undeniably pretty, it is the aquatic equivalent of dandelions in terms of dominating its habitat. This plant is widespread in south Pacific County. In the past year, a large area of it was eradicated from a wetland just east of the Chinook tunnel. It remains common in other places — the wetlands in Beards Hollow, for example.

If pulling or digging yellow flag, care should be used to protect the skin as resins in the leaves and rhizomes can cause irritation. Because rhizome fragments can grow to form new plants, all rhizome fragments must be carefully removed.

• Hoary alyssum invades pastures. Livestock have been known to become intoxicated after eating this weed. It is a growing problem in northeast Washington.

• Annual bugloss can be a problem in cropland, particularly small grains. It has been found in Eastern Washington.

• Ravenna grass grows up to 13-feet tall in ditches, marshes and wetlands. The plant was discovered growing in 2012 in Benton County. Later, it was found in Franklin and Yakima counties.

• Italian arum has been found in several Western Washington counties, particularly in Skamania County. Horses can be poisoned by eating the plant, according to a New Zealand report.

• Myrtle spunge exudes a milky sap that irritates the skin. The largest infestation was in Okanogan County, according to a 2016 report compiled by the agriculture department.

• Spurge Laurel is an ornamental shrub found in Western Washington, particularly in the San Juan Islands and urban King County forests. The shrub produces toxic but bitter berries, so fatal consumption is unlikely.

• Small-flowered jewelweed was discovered in two places in King County. The weed has a shallow root system and can be pulled easily from damp soil.

• American and South American spongeplants grow in dense mats in slow-moving water. The American spongeplant grows as a native species in the Southeastern U.S., but is an invasive aquatic species in Washington.

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