The Hurly-Burly

The fields of bastard cabbage around Austin might seem too daunting to remove, but Joan Singh, Parks Grounds Manager for the Austin Parks and Recreation Department, has a suggestion. If you’re using a park like Mabel Davis anyway, take a minute to remove an invasive  plant while you’re there.

What’s important to preventing the spread of many invasive plants is to keep them from reseeding, Singh says. Bastard cabbage grows, flowers and goes to seed very quickly, producing vast numbers of tiny seeds. (See photos taken Feb. 18 and March 25 to see how fast bastard cabbage has overtaken a field next to Parker Lane.) It would be best to remove the plant, roots and all, but even just removing the flowering top of a plant can help keep the numbers down in the future.

That’s also true of another invasive plant showing up in the area, Malta star-thistle (Centaurea melitensis), says Singh. It’s easy to recognize because native yellow-flowering thistles are uncommon in this area.

Malta star-thistle is an invasive, non-native plant. Texas has no native thistles with yellow flowers, says Joan Singh with the Austin Parks and Recreation Department.

Individuals can make a difference, though a group effort to remove invasive plants from a park would be ideal. Singh says that if you give her 24 hours’ notice, she can deliver plastic bags to dispose of the plant debris. Get rid of the plants in the trash, because the seeds can spread if they make their way into recycled mulch. Leave bags near trash receptacles in the park, near a trailhead or in another logical place, and let Singh know where they are so that city crews can remove them. You can contact her at joan.singh@austintexas.gov or 974-6044.

There’s a pretty plant blooming all over Austin, but don’t be fooled by its good looks. Underneath its veil of yellow flowers is a killer.

An invasive plant called Rapistrum rugosum (aka bastard cabbage, turnip weed or Mediterranean mustard) has taken advantage of a wild year in weather. Last year’s exceptional drought knocked back many native plants, and this year’s wet winter has allowed this invader to grow out of control, shading the ground with its large leaves and keeping the seeds of native plants from germinating. Where fields ought to be filled with bluebonnets, Indian paintbrushes and other wildflowers, this plant from Europe and North Africa has proliferated, crowding out our Texas natives.

The invasive plant commonly known as bastard cabbage has overtaken the wildflower area and many more acres at Mabel Davis District Park. (Click to enlarge.)

Can you find the bluebonnets in this photo? There aren't very many. That's because bastard cabbage has proliferated all along the trail in Mabel Davis Park, crowding out the native wildflowers. (Click to enlarge)

Scientists aren’t sure how bastard cabbage arrived, but they do know how to keep it from spreading: Don’t let it go to seed.

That’s easier said than done. If the plant is sprayed with herbicide but not removed, its seeds might have matured enough to keep spreading the scourge.  (It’s resistant to many herbicides, anyway. Just ask the highway departments of most of the Western states.) And there probably are already seeds in the ground, waiting for another year.

The best approach, according to Damon Waitt, is to manually remove the plant, tap root and all. Waitt, an invasive-plant specialist at the Lady Bird Johnson Wildflower Center, was interviewed by KXAN on Friday. As he told KXAN, “On a scale of 1-to-10, I’m at about 9.5 right now. If we don’t do something about this, we’re going to have to say goodbye to our Texas wildflowers, including bluebonnets.

Volunteers have been working hard to remove this plant from parks this spring. On March 24, a Boy Scout troop helped a group of Texas Master Naturalists pull up bastard cabbage by the roots at Blanco State Park. See what a big difference they made in this blog from writer and master-naturalist-in-training Sheryl Smith-Rodgers.

Learn more about bastard cabbage at this fact sheet from the Plant Conservation Alliance, a consortium of 10 federal agencies and more than 270 other organizations, including arboretums, foundations, plant societies and scientific groups.

Look for the tiny trail walker to get a sense of how expansive the invasion of bastard cabbage is in Mabel Davis Park. (Click to enlarge.)

Don’t let this plant get so much as a toe-hold on your property, and if you want to make a bigger difference, gather a group of volunteers to remove it from public lands such as  Mabel Davis Park. The long tap root will be easiest to remove when the ground is soft, within a few days after a rain. Be sure to dispose of plants in the trash.

There is hope, though. Bastard cabbage is one of the plants being researched by the Wildflower Center’s invasive species program, which has found evidence that it can be out-competed by over-sowing with the seeds of some native wildflowers, such as Indian blanket.  So do your part to keep Austin weird and wild.