New ‘Super Bloom’ Cropping up Around Santa Monica Mountains: Invasive Weeds

A series of spectacular “super blooms” have brought beautiful wildflowers to Southern California this spring, but a new one popping up around the Santa Monica Mountains has scientists concerned.

Hillsides that were scorched from the Woolsey Fire just a few short months ago are now covered with what appear to be bright yellow flowers — but they’re not wildflowers at all, according to biologists and ecologists.

Rather, these bright green stems with the tiny flowers on top are a pernicious weed known as Brassica nigra, or black mustard. And they’ll eventually leave behind “a forest of dead brown stalks,” officials with the Santa Monica Mountains National Recreation Area said in a news release on Wednesday.

The invasive, non-native plants have been springing up recently along the 101 Freeway, Pacific Coast Highway and throughout the Santa Monica Mountains, leaving hillsides covered in lush patches of green and yellow.

In fact, their beauty has led many to mistakenly lump the weeds together with wildflowers like poppies, lupines or phacelias.

“They contribute to the bucolic aspect of the rural countryside,” the release stated, noting that — however pretty the plants may appear — they “are known to push out native vegetation.”

What’s more, stalks of black mustard tend to be thick and grow closely together, making activities such as hiking and mountain biking virtually impossible on some local trails.

But the plants will present a much larger threat in the months ahead when they dry out and become fuel for brush fires, scientists warn.

“In a couple of months, the mustard will dry out, turn brown and become tinder for wildfire,” Joseph Algiers, a restoration ecologist for Santa Monica Mountains National Recreation Area, said in the release. “Sadly, newly burned sites are more subject to invasion.”

Roughly 83 percent of national park land within the recreation area was scorched by last November Woolsey Fire. The deadly blaze burned more than 150 square miles and destroyed hundreds of homes and other structures in Los Angeles and Ventura counties.

There are roughly 300 non-native species being monitored in the Santa Monica Mountains, including a core group known as the “evil 25,” according to Algiers.

Park staff and volunteers are working diligently to combat the spread of the plants.

Black mustard, however, is not on the list. As Algiers explained, “It would probably be easier to get another man on the moon than to get rid of this invasive plant on a regional scale.”

Even though there’s little to be done about the pernicious weed, Algiers said it’s important for the public to know the plant’s short-term and lingering effects.

“This brief moment of beauty will be followed by fields of dead stalks for several years to come,” he said.

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