The bright yellow flowers blanketing LA hills are actually invasive—and ‘evil’

Southern California residents have been treated to a rare explosion of wildflower blooms brought on by one of the wettest winters on record.

But park rangers in the Santa Monica Mountains National Recreation Area say the rain has also fueled growth that could ravage the local ecosystem.

The bight yellow buds that line trails in Griffith Park and cover hillsides along the 101 Freeway, Pacific Coast Highway, and Mulholland Highway, are actually a pernicious weed called black mustard.

The invasive species siphons resources away from native plants, forcing them out of the area and affecting the habitats of local plants and animals. Mustard, which can grow up to 10 feet is tall, is likely to dry up in the summer months, providing fuel for wildfires.

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

Officials have narrowed the list of more than 300 non-native species present in the area to a group of the most persistent and dangerous offenders. They call them “the Evil 25.”

Courtesy of National Park Service

The most-wanted list includes heavies like periwinkle, cape ivy, Spanish broom, fountain grass, pampas grass, Russian knapweed, and artichoke thistle.

But black mustard is so ubiquitous that it’s not on the list.

“It would probably be easier to get another man on the moon than to get rid of this invasive plant on a regional scale,” Algiers says.

There are, however, more newly introduced invasive plants that can be managed. Algiers and a crew of volunteers will focus on those. About twice a month, they will pull weeds and plant natives species. To participate, email Algiers at joseph_algiers@nps.gov.