Those yellow wildflowers you see everywhere are bad for the environment — but they're here to stay

The so-called "superbloom" of California poppies may not be happening this year, but no doubt you've been seeing many majestic hillsides covered in yellow wildflowers all over SoCal.

They're called black mustard. These spindly plants with small, sparse clumps of flowers can easily shoot up to over 6 feet tall in a single year and spread as wide as the eyes can see. While they are a sight to behold, the plants cause tremendous harm by edging out native plants and are ready fuel for wildfires.

The origin of black mustard

Known scientifically as brassica nigra, black mustard is related to grocery store mainstays like Brussels sprouts and cauliflowers. As such, the plant is edible and as its namesake suggests, the seeds can be used to make spicy mustard.

But the plant came from a place far from our native soil, brought here centuries ago by Spanish missionaries as a food crop, said Matt Loftis, a manager of Mountain Forestry Department at TreePeople. It has since thrived unchecked, aided by a similar Mediterranean climate in Southern California.

"Since it's non-native, it's cheating all those systems of checks and balances that all the native flora and fauna have to go through," Loftis said. "Mustard can kind of skip all that because it's not having to compete with other insects and vertebrates that's eating or parasitizing it."

The invasive plant also produces a chemical that suppresses the growth of native plants around it. Coupled with its "live fast, die young" lifestyle, by the time summer rolls around, dried out black mustard can turn any landscape it graces into combustible tinder.

"It ignites really easily, it burns really hot, and fire can spread through it really quickly, especially if you have wind-driven fires we get from the Santa Anas in September and October," said Loftis.

Black mustard plants growing wild in Elysian Park in 2023.

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Fiona Ng

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LAist

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A point of no return?

One place that has seen its share of the plant is the Santa Monica Mountains.

"We have a couple of different mustards that are dominant in our mountains and black mustard is probably the most dominant," said Joey Algiers, a restoration ecologist with the National Park Service for the Santa Monica Mountains National Recreation Area.

The plant has become so widespread and ubiquitous there that its eradication has become a losing battle.

"We focus on those [invasive plants] that are the most ecologically damaging and that we actually have a chance at controlling," said Algiers. "We do control them when they occur next to sensitive species or habitat, but large scale removal of this species is just astronomical."

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Courtesy National Park Service

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Algiers said ecologists have been looking into cultivating native seeds as a potential solution.

"When it comes to restoration, oftentimes people think about planting trees," Algiers said, which is labor and time intensive. "If you have enough native seed, you can cover acres and acres of large landscapes."

"Right now we're in the process of trying to develop the ammunition, if you will," he added.

Ways we can help

Still, Algiers and Loftis said everyone can pitch in to stop the mustard's spread.

"Invasive species and weeds don't stay put," Algiers said.

So go ahead and get rid of the plant if you see it in your yard or your neighborhood. Just be sure to do it before it sets seed.

"You can cut it, you can dig it, you can weed whack it, you can pull it, you can eat it," Loftis said. "I'm just waiting for black mustard to be the next health trend in L.A."