Western sycamore’s fall color display

Posted: October 20th, 2017 | Columns, Featured, Mission Trails - Trail Guide | No Comments

By Audrey F. Baker

A festival of autumn color is underway at Mission Trails Regional Park. Flat-top buckwheat flaunts its maroon seed heads. Brilliant yellow goldenbush is captivating arsenals of late-season pollinators. Deciduous trees like Fremont cottonwood are exhibiting their colorful conversion into dormancy. Juxtaposed against backgrounds of the deep greens of coast live oak, these and other offerings make a rich visual contrast and present the spectrum of fall color.

Psychologists tell us that observing nature’s vivid color and contrast stimulates memory and imagination, and prepares us for changes in the future. Engaging us and releasing our inner poet and philosopher, it serves as a stress reliever.

Nuttall’s woodpecker in a Western sycamore (Photo by Wendy Esterly)

Western sycamore (Platanus racemosa) is putting on a spectacle befitting an ancient ritual.

As members of one of Earth’s oldest clan of trees, Platanaceae, paleobotanists can literally trace back its roots over 100 million years. Also known as the Plane Tree Family, this exclusive group has only one genus, sycamores. Of the eight known species in the Northern Hemisphere, six are native to North America.

Commonly named the California sycamore, our sycamore variety’s native range begins at the streams and tributaries of the upper Sacramento River. It tracks the lower Sierra Nevada and at Monterey transitions into the coastal ranges, and ultimately into northwestern Mexico.

Whether you call it California Plane Tree or Spanish Aliso, the Western sycamore is a historic component of the California landscape, found along streams, rocky canyons, moist valleys, and arid foothills. It grows on bottomlands where soil is deep and rich, yet can tolerate sand, clay and seasonal flooding. The main requirement is moist but well-drained sites.

Ours is smaller than its eastern mixed hardwood forest cousin the American sycamore (P. occidentalis) that routinely grows to 100-foot in height. The California typically ranges from 30-to-60-feet tall with a 3-feet-across trunk. Some exceed 115-feet stature.

These are dramatic, intriguing and aesthetically beautiful trees. The exfoliating bark exhibits a mottled collage of color. Predominantly white, it fuses into a swirling pattern of grays, browns and tan with hints of yellow to green hues. The older, darker bark drops, often in large sheaths.

Despite heavy spreading branches, the trees have a graceful appearance, often displaying a “leaning habit.” Ball-shaped seed clusters developed from female flowers of April dangle like three loose beads on a chain and persist after leaves fall.

Western sycamores dress in spectacular lime-colored five-tipped palmately lobed leaves bearing lightly serrated edges and are reminiscent of an oversized outstretched human hand. The leaves may be up to nine inches, qualifying the Western Plane Tree as North America’s largest native broadleaf tree. One leaf found at Mission Trails had a 15-inch diameter!

With an astounding two-feet-per-year spring/summer growth rate, California sycamore is formidable. It can live more than 200 years. Individuals reportedly exceed 500. The ever-crafty plant has developed several strategies to maintain its long line of succession. The seed ball houses multiple seed capsules, each having one long and beaked seed with basal hairs that aid in disbursement.

Despite this output, it can clone itself. A fallen twig can make a tree. As an aggressive stump starter, it is not easily deterred by damage.

Other adaptations include high tolerance for drought and for exhaust fumes and pollution.

Welcoming warped, twisted branches provide wildlife shelter, food and nesting sites and are extensively used by owls, hawks, woodpeckers, ospreys, hummingbirds and songbirds. For western tiger swallowtail butterflies, sycamore leaves furnish larval food. Many mammals dine on its twigs and bark. A host of invertebrates gorge in its soil.

Autumn signals a rest period. Leaves turn yellow, orange and brown, adding enhanced color, seemingly to celebrate another successful year. In falling, leaves create a rich groundcover, conserving moisture, enhancing top soil and keeping roots cool. Sycamores also shed bark and branches prolifically.

Warm, rich fall colors exude a sense of comfort directly impacting emotions. Reds evoke passion, orange suggests brightness, yellow cheers and chocolatey brown naturally stabilizes. It’s all here at Mission Trails Park. Join our trail guide-led walks and relax in colorful nature!

— Audrey F. Baker is a trail guide at Mission Trails Regional Park. Check the MTRP events calendar published here or at or call 619-668-3281 for more information on the park’s free trail guide-led nature walks and opportunities to learn more about natural Southern California. Special walks can be arranged for any club, group, business or school by contacting Ranger Chris Axtmann at 619-668-2746 or at

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