Shiny Geranium – April 2017 Weed of the Month

With shiny geranium, appearances are deceiving. Don’t let the plant’s small size or delicate pink flowers fool you. To quote Ed Alverson, a botanist from Oregon who has extensive experience battling shiny geranium, “this is pretty much the most diabolical invasive plant I’ve ever encountered”. He adds, “In my 3 decades of experience with this species I’ve not seen anyone successfully “control” it, anywhere or any time. Not that it is impossible, I’ve just not seen anyone take it as seriously as is necessary, especially early on”.

shiny geranium growing in a patch near the West Seattle Bridge.

Shiny geranium near the West Seattle bridge. Photo by Maria Winkler.

Shiny geranium (Geranium lucidum) was probably brought to North America by accident, first identified in the United States in 1971 growing in a cow pasture in Oregon. Since that time, it has spread to habitats that had previously been fairly resistant to invaders such as western Oregon’s oak woodlands.

In Washington, shiny geranium has been on the rise since it was first collected in the state in 2006. When it was added to the Washington State Noxious Weed List in 2009, it was classified as a Class A noxious weed because it seemed to be very limited in distribution. Unfortunately, it has been found over a much wider area since then and was moved to the Class B list in 2015. Sadly, on a statewide basis, Ed’s experience is holding true as the efforts in Washington have switched from statewide eradication to preventing further spread and trying to reduce it where we can.

Even though this plant has been down-graded in Washington, our goal in King County is still to eradicate it as best we can. As of this writing, we have records of 27 infestations, seven of which are on roadsides and the rest on a variety of different properties, including residential yards, city parks, schools, and even a former nursery site.

When Ed gave us his warning about shiny geranium, he also notified us about two patches of shiny geranium he spotted along King County roadsides, one on Snoqualmie Ridge he found last June and another in Sammamish a few weeks ago. Both sites were confirmed and are now being managed, hopefully on the way to being eradicated. These roadside locations pose a big threat of spread as roadside management often includes mowing, which can move the weeds farther.

In addition to roadside areas, many locations in King County have been linked to contaminated nursery plants or mulch materials.

Shiny geranium seedlings showed up in a recently mulched area in the West Duwamish Greenbelt in Seattle this year. Always check your pots and mulched areas for new intruders like shiny geranium! Photo by Maria Winkler.

Shiny geranium seedlings showed up in a recently mulched area in the West Duwamish Greenbelt in Seattle this year. Always check your pots and mulched areas for new intruders like shiny geranium! Photo by Maria Winkler.

One of the first infestations we learned about was the Thornton Creek daylighting project near Northgate Mall. Photo by Sasha Shaw.

One of the first shiny geranium infestations we learned about in King County was the Thornton Creek daylighting project near Northgate Mall. Photo by Sasha Shaw.

Shiny geranium appears to have been brought in with either gravel or plants that were used on a “living wall” on the sides of the daylighted creek. Photo by Sasha Shaw.

Shiny geranium appears to have been brought in with either gravel or plants that were used on a “living wall” on the sides of the daylighted creek. Photo by Sasha Shaw.

Perhaps the most unusual infestation we found was covering the roof of a house. Hours of control on a ladder paid off. Photo by Karen Peterson.

Perhaps the most unusual infestation we found was covering the roof of a house. Hours of control on a ladder paid off. Photo by Karen Peterson.

This year there were only a few plants coming up in the gutters. Photo by Karen Peterson.

This year there were only a few plants coming up in the gutters. Photo by Karen Peterson.

Shiny geranium identification is not difficult, however it does take attention to detail.

Shiny geranium look-alikes include dovefoot geranium and herb-Robert (stinky bob), both also weedy geranium species, but that are much more widespread.

Dovefoot (Geranium molle) has fuzzy leaves and appears to have 10 petals because they are notched. Photo by Bruce Newhouse.

Dovefoot (Geranium molle) has fuzzy leaves and appears to have 10 petals because they are notched. Photo by Bruce Newhouse.

Herb-Robert has hairy stems, finely dissected leaves and has a strong odor when crushed. Photo by Sasha Shaw.

Herb-Robert has hairy stems, finely dissected leaves and has a strong odor when crushed. Photo by Sasha Shaw.

The plants are most obvious in spring when they grow densely and capitalize on early season moisture. Photo by Karen Peterson.

The plants are most obvious in spring when they grow densely and capitalize on early season moisture. Photo by Karen Peterson.

By summer time, the plants have mostly gone to seed and tend to fade back into the background until the new plants germinate following fall rains. Photo by Matt Below.

By summer time, the plants have mostly gone to seed and tend to fade back into the background until the new plants germinate following fall rains. Photo by Matt Below.

As seen in this roadside patch, shiny geranium is also very capable of dominating in sunny areas as well as shady areas. Plants turn bright red in the sunlight as they go to seed. Photo by Matt Below.

As seen in this roadside patch, shiny geranium is also very capable of dominating in sunny areas as well as shady areas. Plants turn bright red in the sunlight as they go to seed. Photo by Matt Below.

Plants spread by seeds that are forcefully ejected up to 20 feet away even without wind. Also, the seeds are easily transported by animals, people, and in soil. On top of all that, seeds are highly viable and plants germinate several times a year. As a result, populations rapidly expand from a few plants to large, dense patches very quickly.

Shiny geranium is an annual (or sometimes biennial) and can be pulled out fairly easily, although it has a tendency to break off at the crown and can re-sprout if not carefully removed. Photo by Sasha Shaw.

Shiny geranium is an annual (or sometimes biennial) and can be pulled out fairly easily, although it has a tendency to break off at the crown and can re-sprout if not carefully removed. Photo by Sasha Shaw.

Make sure to bag up shiny geranium after removing to keep it from spreading. Photo by Sasha Shaw.

Make sure to bag up shiny geranium after removing to keep it from spreading. Photo by Sasha Shaw.

Bagged up plants need to be discarded in the trash – not left behind where they will just keep growing. Photo by Matt Below.

Bagged up plants need to be discarded in the trash – not left behind where they will just keep growing. Photo by Matt Below.

Large infestations of shiny geranium have many thousands of plants growing very densely.

Large infestations of shiny geranium have many thousands of plants growing very densely.

For large, dense infestations, herbicide sprayed in fall or early spring before most other plants are growing is the most effective method.

For large, dense infestations, herbicide sprayed in fall or early spring before most other plants are growing is the most effective method.

If you see any shiny geranium in King County, Washington, please report it to us as soon as possible so we can follow up on it and prevent it from spreading further. Our website has photos and information on shiny geranium as well as links to other great resources on this plant. In Washington outside of King County, please visit the Washington State Weed Board website. In Oregon, make sure to visit the Oregon Department of Agriculture website for more information. Feel free to contact us at King County Noxious Weeds if you have any questions about this plant or any other noxious weeds.



Categories: Noxious Weed of the Month, Program News, Tips, Weed Identification

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