The garden's organizing principle is geographic. Walk its paths and you move through ten sections, each representing a distinct natural region of the state: Southern California's drought-adapted scrub gives way to the Shasta-Klamath corridor's conifers, then the Valley-Foothill zone, the Santa Lucia mountains, the Channel Islands, the Sierra, the Redwood belt, the Sea Bluff, the Pacific Rain Forest, and the Franciscan formation unique to the San Francisco Bay Area. Subsections for Antioch Dunes, coastal dunes, and a pond fill out the edges. The effect is like a botanical compression of a 700-mile drive from the Mexican border to the Oregon line, concentrated into a quiet hillside where you can walk from chaparral to old-growth atmosphere in minutes.

What sets this garden apart from other botanical collections is its single-minded focus on plants native to California -- and the depth of its holdings in certain groups. The manzanita collection may be the most complete anywhere. Nearly all of the state's conifer and oak species grow here, along with a strong collection of wild lilacs in the genus Ceanothus. Representatives of some 300 rare and endangered vascular plant taxa make their home in the garden, from the fuchsia-flowered gooseberry to the western leatherwood, from matilija poppies with their tissue-paper petals to woolly blue curls that hum with pollinators in summer. The list of collected species reads like a field guide to everything that grows between the Pacific and the Sierra crest: shooting stars, fritillarias, fawn lilies, brodiaeas, mariposa tulips, California fuchsias, and dozens more.

James Roof did more than tend a garden. As its founding director, he turned the Tilden botanic collection into an argument for why California's native flora deserved attention and protection at a time when most landscaping favored imported species. The garden became a gathering place for botanists, horticulturists, and conservationists who shared that conviction. On August 12, 1965, the California Native Plant Society was incorporated -- and the Tilden Botanic Garden is recognized as its birthplace. The CNPS has since grown into one of the most influential native plant advocacy organizations in the country, with chapters across the state and a publication record that shapes both policy and practice. That a 10-acre WPA garden in the Berkeley Hills incubated a statewide conservation movement says something about what happens when the right plants, the right people, and the right place converge.

The garden does not compete for attention. There is no gift shop spectacle, no themed attraction. Redwoods shade the forest section with a quiet that feels earned rather than designed. Gray mule's ears bloom in their season; California poppies flare orange against the hillside and fade. The WPA terracing from the early 1940s still holds, shaping the flow of paths and water. Visitors come to learn plant identification, to sketch, to sit on benches positioned where the light falls through canopy gaps at certain hours. Managed by the East Bay Regional Park District and supported by the Friends of the Regional Parks Botanic Garden, the collection continues to expand -- adding native bunchgrasses and aquatics to keep pace with evolving conservation priorities. For a place built by Depression-era labor and Depression-era idealism, the garden has aged remarkably well, its mission unchanged after more than eight decades: to show Californians what California actually looks like when it grows on its own terms.