South entrance of Regency (GPS: 1531 Regency Court, El Cerrito)
“Guerrilla” workparty (expect lots of poison oak)
While updating the native plant list in the HNA, we discovered a beautiful plant community near Hidden Valley (parallel to Kent Drive): sword ferns, goldback fern, gooseberries, oceanspray, monkeyflowers, yerba buena, beeplant, coffeeberry, American yellowrocket, woodland strawberries, creeping snowberry, blue elderberry, hedgenettle, pink honeysuckle… and, of course, plenty of poison oak.
Unfortunately, there is also a large patch of crofton weed starting to spread. To prevent further invasion, we need to act now. We’re looking for brave weed warriors willing to take it on. Happy to share tips to avoid getting a rash after.

Below is a picture of Ageratina adenophora (synonym Eupatorium adenophorum), commonly known as Crofton weed or Mexican Devil. It is a fast-spreading perennial herb native to Central America. It has become a highly invasive species in many parts of the world, including California, where it thrives in disturbed areas, roadsides, and open hillsides. The plant produces clusters of small, fluffy white flowers and spreads both by seeds and vegetative growth, allowing it to form dense stands that outcompete native vegetation.

Crofton weed is of particular concern in restoration areas because it reduces biodiversity, alters soil conditions, and can interfere with natural plant succession. Effective management typically involves early detection, repeated removal before seed set, and long-term monitoring to prevent reestablishment.