Take a hike through a California oak forest and you might come upon rocky outcroppings incised with one or more shallow, circular holes. These depressions, known as bedrock mortars, are not natural geological features. Instead, they were created hundreds of years ago as Native Americans used stone surfaces to pound and grind acorns, a dietary staple for tribes throughout the state.
From the Kumeyaay in San Diego County to the Yurok and Hoopa (or Hupa) on the North Coast, 75 percent of California’s Indigenous people relied on acorns as one of their primary foods. There’s evidence that Native Americans in the state used acorns for at least 9,000 years. In fact, acorns are found in greater quantities than any other food at California archaeological sites.
Twenty different oak tree species grow in California, with stands of coast live oak stretching from Northern California’s Mendocino County south into Mexico, huge valley oaks ranging from Shasta County out to the Channel Islands, and California black oaks growing along a nearly 800-mile band extending from the Cascade Range into the Sierra Nevada and south to San Diego County.
While other traditional foods, such as salmon and abalone, were more restricted to specific regions, Native Americans’ reliance on acorns crossed both climatic and cultural lines as the nuts’ variety and availability made them part of the daily lives of Indigenous peoples across California. Even with all of the changes that have come to the state, acorns continue to play a role for today’s Native American cultures in California.
An Original Superfood
As a food source, acorns offered numerous advantages. In most years, they are abundant (depending on the species, mature oaks can produce 1,000 pounds of acorns). Rich in carbohydrates, protein, and fat, as well as minerals and vitamins, acorns are highly nutritious and can also be stored for later use, sometimes for as long as 10 years. The nut’s only downside is its high tannin content, which gives raw acorns a bitter taste. Considerable work is required to convert the acorn into palatable food.
Collecting acorns, typically by knocking them from branches with long poles or by climbing trees, was a major community activity in late summer and autumn. Once harvested, the acorns were dried in the sun or by fires to inhibit spoilage while stored. Acorns were typically roasted to kill off any bugs and, after shelling, ground with a mortar and pestle or milling stone, then sifted into a fine flour. Native people used water to leach tannins from the flour to prepare it for use in a porridge-like mush, soups, and breads.
Not all acorns, however, are the same. Black oak acorns, a favorite of the Yokuts in the Central Valley and Sierra foothills, are known for their high fat content, while Gambel oak acorns naturally taste sweeter and don’t require leaching. Tanoak acorns were coveted for their flavor by tribes within the trees’ range, such as the Salinan, Chumash, Ohlone/Costanoan (among them, today’s Amah Mutsun Tribal Band), Pomo (including the federally recognized Kashia Band and the Graton Ranchiera), Yurok, and Hoopa.
Some of California’s Indigenous people also used tanoak acorns for medicinal reasons, such as to treat coughs. Many tribes, most famously the Pomo, crafted beautiful twined and coiled baskets to use for gathering acorns, sifting flour, food storage, and preparing soups.
California tribes actively managed oak stands to promote production while leaving enough acorns unharvested to sustain deer and other wildlife, which also depended on them for food. Tribes lit small, low-intensity fires in forests to clear out competing vegetation, encourage seedling growth, and control pests like weevils and worms that fed on acorns.
Studies have shown that this “cultural burning practice” increases acorn production and results in healthier forests. Today, as tribes partner with governmental agencies, this traditional ecological knowledge is being used to manage oaks at several California locations. In Sierra National Forest, members of the North Fork Rancheria of Mono Indians of California have worked with forestry officials to promote black oak acorn production in parts of the Sierra Nevada by removing invasive and competing plants and lighting low-intensity burns. A similar project is taking place at the Greenville Rancheria in Plumas National Forest.
Acorn Experiences in California
Despite limited access for harvesting in oak woodlands, many of which are on public lands that restrict gathering, acorns remain a part of Indigenous life in California. During the Fall Gathering at the Malki Museumon the Morongo Indian Reservation near Banning, you can observe the ways the Cahuilla Indians harvested and processed acorns and also taste wewish, an acorn mush. In September at the Tuolumne Rancheria in Gold Country, the Tuolumne Band of Me-Wuk Indians hosts its annual Acorn Festival, which celebrates the black oak acorn harvest with traditional dances, crafts, and food booths. Visitors can taste nupa, an acorn soup.
Other events include Sacramento’s California State Indian Museum’s annual Acorn Day in October, where you can watch demonstrations of acorn processing. At the annual Acorn Day in November at Ukiah’s Grace Hudson Museum, try your own hand working with acorns and watch Yuki Dancers from Mendocino County’s confederated Round Valley Indian Tribes.
For a contemporary take on acorn-based foods, the Santa Barbara restaurant Barbareño—which draws its inspiration from a diverse range of Central Coast culinary traditions—serves an acorn agnolotti made with local mushrooms. At Berkeley’s Cafe Ohlone, the changing seasonal menu includes delicacies such as tanoak acorn bisque, black oak acorn bread, and brownies made with tanoak flour.
And at Indian Grinding Rock State Historic Park 8 miles east of Jackson in Amador County, you’ll find North America’s largest collection of bedrock mortars. Once used for grinding acorns and seeds, 1,185 mortars have been pounded into the park’s limestone outcroppings. In September, the Ione Band of Miwok Indians comes to the park to celebrate the acorn harvest during its Big Time at Chaw’Se celebration, which is open to the public.