California Sycamore

Platanus racemosa

tree with 3 stemmed leaves
La Orilla trailhead | September 2016

“In the place that is my own place, whose earth
I am shaped in and must bear, there is an old tree growing,
a great sycamore that is a wondrous healer of itself.

Over all its scars has come the seamless white
of the bark. It bears the gnarls of its history
healed over. It has risen to a strange perfection
in the warp and bending of its long growth.”

excerpted from The Sycamore by Wendell Berry.

Other Common Names:

Western sycamore, aliso

Description 4,11,23,59

California sycamore (Platanus racemosa) is a majestic tree, up to 100 feet (32 m) in height and more than five feet (1.5 m) in diameter. A sycamore may have one or several trunks, which may be erect or wildly twisted and bent. The bark is smooth and pale with patches of tan and gray, sometimes tinged with pink and green; the bark has been likened to army camouflage. 317 The bark continually peels away in thin stiff sheets. Near the base of the trunk, the bark is often gray and rough.

The mature green leaves are large, reaching 10 inches (25 cm) long and 12 inches (30 cm) wide. They are  palmately cut into three to five lobes, similar to maple leaves; the terminal lobe is 1/3 – 2/3 the leaf length. Young leaves are velvety with a dense covering of hairs that are lost as leaves age, especially on the upper surfaces which become completely smooth. Leaf petioles are 3/4 – 3 inches (2-8 cm) long. At the base of each petiole, there is a jaggedly rounded, leaf-like stipule that encircles the stem and may fall away as the leaf matures.  Leaf petioles are unusual in that they wrap around the supporting twig, concealing next year’s axial bud. Like many of our riparian trees, California sycamores are winter deciduous; the leaves often turn yellow and gold before they drop.

The flowers of California sycamore occur in dense, spherical clusters, several of which dangle from a lax peduncle up to three inches (8 cm) long. There may be as many as 100 tiny flowers in one cluster. Male and female flowers occur in different clusters on the same tree. Male clusters are greenish-tan, less than 1/2 inch in diameter; the peduncle is more or less zig-zaged. Individual male flowers are difficult to distinguish. After release of pollen, male clusters drop from the tree. Female clusters are somewhat easier to decipher. Petals are absent but each flower has up to 9 pistils each with a bright red, curved style. Together, these tiny styles give the female cluster a characteristic red, fuzzy look. Flowers are wind pollinated. Sycamore flowers between  Feb, and April.1

As the seeds develop, the spherical clusters enlarge to 1 inch or more (2-3 cm). Each seed capsule is one-seeded, dry, tan and elongate with a “beak” (the persistent style) and basal bristle of golden brown basal hairs that aid dispersal by wind. Seed heads persist on the tree through the winter, slowly disintegrating, allowing the seeds to disperse.

red dandelion like bulbs

Female flower clusters | La Orilla trailhead | February 2011

small green balls connected

Male flower clusters | Nature Center | February 2017

close up of bulb like stem

Developing seed cluster | La Orilla trailhead | February 2017

Distribution 7,89

California sycamore is native to the western United States, northern Baja, and northwestern Mexico, generally below 4000 feet (1250 m). Except for in the most northern and most eastern counties, it is found throughout California, primarily along the coast and around the Central Valley. It is associated with a variety of vegetation types, but its rather shallow roots restrict it to stream and lake beds and other areas with a shallow water table.

In the Reserve, California sycamore is scattered among our riparian areas: associated with the willows at the Nature Center, and in the East Basin along Escondido Creek and along the southeast side of the marsh between Santa Helena and the La Orilla trailhead

Classification 2,4,11,44

California sycamore belongs to the sycamore family (Platanaceae), an old, primitive family of the temperate and subtropical Northern Hemisphere. There is a single genus, Platanus, with six to ten species.

Members of the sycamore family are trees with pale, flaking bark and large, flat, simple, alternate deciduous leaves. They have flowers in dense, spherical clusters of male or female flowers that dangle from drooping stems. Fruits are achenes. The development of the axilary bud inside the basal sheath of a leaf stem is unique to this family.11

In this country, one of the best known members of this family is the London planetree, thought to be a hybrid of the eastern sycamore (Platanus occidentalis) and the oriental plane (P. orientalis).41,44 The London planetree is tolerant of poor soil and pollution, making it a popular urban tree in the East.317

Jepson eFlora Taxon Page
close up of leaf blooming

Stipules and clasping petioles | La Orilla trailhead | September 2016

close up of tree leaves, leaves split 4 ways

La Orilla trailhead | August 2016

looking up into tree and branches

La Orilla trailhead | February 2017


Tree bark has been likened to the skin of an animal, and it provides many of the same protective functions, offering protection from insects and fungal infections and protection from sun burn and water loss.321

The outer layer of bark is dead, produced by a ring of dividing cells (cork cambium) below the bark. The bark of most saplings is smooth. As the tree grows in diameter, the outer bark must stretch or crack or peel away to make room for this new growth, and new bark is created by the cork cambium. This process of cracking and peeling takes different forms on different species and gives rise to the wide variety of bark patterns.322

The colorful sycamore bark is thin and constantly shedding. The thin bark may be an adaptation to the riparian habitat where reliable water supplies require less protection from water loss. When water is plentiful, the ability of a sycamore to accelerate the uptake and elimination of gases, including water vapor, by exchanging them through the trunk may actually allow the tree to grow faster, which, in turn, necessitates more rapid bark loss.317

The areas of gray, roughened bark that are occasionally found around the base of sycamores, or in patches further up, are not part of the natural growth process of the tree, but are caused by an insect – the clearwing sycamore borer moth (Synanthedon resplendens).11,59,144,318 An adult lays eggs in cracks and crevices of the bark. The larvae tunnel through and beneath the bark, feeding on the living tissues beneath for about a year and creating a matrix of serpentine tunnels over small areas. Larvae pupates in their tunnels. When ready to emerge, a pupa wriggles to the exit hole where the pupal case splits, releasing the adult moth. The cast off exoskeletons can sometimes be seen protruding from the little exit holes. Sycamores appear quite tolerant of this feeding activity and damage is usually confined to the patches of crumbling, discolored bark.

dried out tree branches

La Orilla trailhead | February 2017

Holes in brown bark

Holes from clearwing moth larvae | La Orilla trailhead | February 2017

bush in a field

Santa Helena trailhead | November 2010

Human Uses

Sycamore wood is pleasantly mottled (“all mixed up”). The Chumash in the Santa Barbara region made wooden bowls from the gnarled branches or burl-like growths.15,75 Wood had to be worked while still green, and a burl at this stage was called hsh’o, which was the same word they used for sycamore. Bowls were described as “polished and perfectly formed as though turned on a lathe, beautiful and with inlay.”75

Several tribes used sycamore branches for the construction of homes and ramadas, and even for wagon wheels.15,272

There are a few references to medicinal use of sycamore bark tea.76,272 In present day Mexico, sycamore bark and roots are boiled for a coffee substitute.76

tall dried out tree in forest

La Orilla trailhead | February 2017

tree in full bloom

La Orilla trailhead | August 2016

New growth of green leaves

Young leaves covered with velvety down | Nature Center | February 2017

Interesting Facts 319,320

St Paul’s Chapel in lower Manhattan was built in 1766 and declared an National Historic Landmark in 1960.41 Before the events of September 11, 2001, St Paul’s was sheltered on the northwest by a huge old sycamore tree. On 9/11, this tree was toppled by the blast from the falling World Trade Center towers, but the branches of the fallen tree provided protection for the chapel and its cemetery. No tombstones were damaged, and the chapel survived with its tall spire intact and without a single broken window.

Artist Steven Tobin made a mold of the 600 pound root ball from which he created a bronze sculpture, Trinity Root, a testament to “life, humanity and the positive response to catastrophe”.320

Root sculpture by Steven Tobin

Trinity Root Sculpture by Steven Stobin

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