One of the most iconic trees of Southern California is the Juglans californica, commonly known as the Southern California black walnut. As trees go, it is fairly small, usually reaching a height and radius that tops out around fifteen meters. It could, alternately, be described as a large shrub — as many specimens have up to five five trunks.
On the Silver Lake passeggiata, I pass two of them, marking the passage of seasons as they drop their leaves, re-grow them, flower, and fruit. Right now they’re dropping those fruits, or walnuts, and the walnuts are turning black. I learned from the Silver Lake Neighborhood Council‘s Green Committee that NELA Alliance are planning to recognize 11 September as Northeast Los Angeles Black Walnut Tree Day. The plan to is to provide education on the uses and benefits of black walnuts, to map black walnuts using iNaturalist, and to offer free, young trees to be planted for those who can commit to nurturing them. It’s scheduled to take place at Ascot Hills Park in El Sereno.
To sign the digital petition to create Northeast Los Angeles Black Walnut Tree Day and to get updates on the campaign, click here.
The Southern California black walnut is endemic to Southern California. It’s a picky plant, generally preferring the northeast faces of hills and mountains in Southern California. There are, in Los Angeles, native stands in the Santa Monica Mountains, Elysian Hills, Puente Hills, Repetto Hills, San Gabriels, San Rafael Hills, Verdugos, and other ranges in the region. It grows in mixed riparian woodlands and single species stands, on both slopes and in valleys. Its why, in Southern California, we have communities with names like Walnut, Walnut Creek, and Nogales High School.
Black Walnuts often grow near oaks and cottonwoods. It is a foundation tree that supports at least 29 species of birds and nearly as many species of moths and butterflies. It is fire retardant and resilient — sometimes able to recover from fires that burn them down to the soil, which it helps anchor, preventing mudslides. Traditionally, they were used as a food source by the region’s indigenous Chumash as well as later arrivals like the Tongva. The nuts are also a food source for ground squirrels and other native rodents. The husks were used to create dye. The bark was used in basket-making. The walnut shells were used in a dice-like game called “pi,” played by the upper world sky people in the Chumash religion.
Southern California Black Walnuts are currently classified as “near threatened” and are thus legally protected by the California Department of Fish and Wildlife, the California Environmental Quality Act, and the City of Los Angeles Tree Protection Ordinance. However, enforcement of their protection is lacking and developers often fell them, either in ignorance or indifference. Furthermore, the City of Los Angeles issues permits to remove these vulnerable trees (that have already lost 31% of their habitat to development) once every 7.2 days on average, according to the Conservation of California Walnut in Eastern Santa Monica Mountains (Nina Noujdina and Travis Longcore, The Urban Wildlands Group, 2022).
Naturally, if you care about vulnerable trees, you may have the impulse to propagate them. I have thought about harvesting black walnuts in the past but found the process daunting. One, since walnuts are used as food by many animals and, potentially, can generate more black walnut trees — it’s important for would-be harvesters to leave the vast majority of walnuts where they fall.