The Redwood Trail San Francisco Botanical Garden At Strybing Arboretum
You are about to explore one of the most remarkable and unique
plant communities in the world. The keystone species of this
community is the Coast Redwood. These trees are the tallest
living things on Earth and among the most well-adapted to their
growing conditions. Stands of Coast Redwoods once ﬂourished
on more than two million acres but have been reduced by
extensive logging during the last 150 years to various isolated
patches in Coastal California, from the Monterey Peninsula south
of San Francisco to Southern Oregon.
The Coast Redwoods here at the San Francisco Botanical Garden
were planted around the turn of the 20th century and are among
the oldest trees in the Garden. More than one hundred species of
associated plants have been added over the past 40 years representing
a typical redwood forest community. Along the trail, you will see signs
explaining the parts of this forest system and the plants that inhabit
it. The plants and other attractions of this walk are numbered to
correspond to their location on the Redwood Trail map. Begin your
walk on the main path to the right of the Redwood Trail sign.
1. Coast Redwoods Sequoia sempervirens
Coast Redwoods mark the entrance to the trail. These tallest
of living trees have thick, reddish-brown bark and small cones
hanging from the branch tips. The redwood bark gets its
characteristic color from tannins which are bitter chemicals that
help the tree resist burning and insect damage. These trees are
native to the protected coastal valleys of northern California and
Oregon and have two closely related cousins: The Giant Sequoia,
Sequoiadendron giganteum, which are native to the Western
Sierra Nevada range and the Dawn Redwood, Metasequoia
glyptostroboides, which are native to China. Both can be seen
here in the San Francisco Botanical Garden along the path that
surrounds the California Native Garden.
Proceed straight ahead to the Nurse Stump.
2. Nurse Stump
Because tannins make the bark of these trees so strong, a stump
from a burned or fallen redwood tree often remains for many years.
The stump ﬁlls with dead leaves and forest debris, which decomposes
creating a coarse soil that nurtures a variety of plants. Among the plants
that grow on the stump are huckleberry, sword fern, redwood sorrel,
Take the path to your left where you will encounter native plants
that are part of the coast redwood community.
On your left is the Flowering Currant.
3. Flowering Currant Ribes sanguineum
Fragrant rosy red ﬂowers and pale green leaves appear on this
deciduous shrub in the late winter or early spring. Small black berries
form in the summer. The alternate, lobed leaves are downy beneath.
Across the path is the Western Swordfern.
4. Western Swordfern Polystichum munitum
Thrive in on the rich, moist forest ﬂoor. This fern usually grows to
a height of two to four feet. It has a projection at the base of each
leaﬂet which resembles the hilt of a sword.
Walk a few feet forward to see the Skunk Cabbage.
5. Skunk Cabbage Lysichiton americanum
Edging the forest stream. The broad deep green leaves and bright
yellow leaf-like spathe of this plant are apparent in the summer
along with the skunk-like odor that gives this plant its name. The
plant has no stem and in winter dies back to the horizontal root. It
favors the damp moist conditions you see it growing in here.
Look to the left of the path for the Western Azalea.
6. Western Azalea Rhododendron occidentale
This deciduous shrub forms dense thickets in redwood forests but
requires sufﬁcient sunlight for its display of large fragrant clusters of
white or pink ﬂowers in early summer.
Continue straight along the path and look to the left for the
7. California Hazelnut Corylus cornuta var. californica
The broad, oval leaves with conspicuous veins and a hairy
appearance are bright green as they emerge in the spring, but
become smooth with age. Male catkins cover this deciduous shrub
in late winter and smaller red female ﬂowers appear on the same
plant. Squirrels and other wildlife enjoy the nuts which follow in
the summer. The nuts were also an important food for the coast
Indians, who ground them into ﬂour for bread. They also used the
stems of this shrub to make baskets.
Continue past the exit path to the Big-Leaf Maple.
8. Big-Leaf Maple Acer macrophyllum
This large which ﬁlls the area to the left of the path, typically grows
at the edge of the redwood forest, reaching for sunlight. The leaf
has ﬁve lobes and turns bright gold before dropping in the fall.
On both sides of the path, ﬁnd Huckleberry.
9. Huckleberry Vaccinium ovatum
This evergreen shrub is one of the most common understory plants
in the redwood forest. Small white bell-shaped ﬂowers adorn it in
spring, followed by deep blue berries in the fall.
To the right of the path, notice the Tanbark Oak.
10. Tanbark Oak Lithocarpus densiﬂorus
This evergreen tree is a member of the oak family, but not a true
oak. It has a straight tall trunk. The smooth gray bark cracks with
age and appears black due to the high tannic acid content. The
tannins from these trees was once used to tan leather. Tanbark oak
leaves have a coarse, saw-toothed edge and a conspicuous vein-like
patterning. It takes two years for a female tanbark oak ﬂower to
mature into an acorn.
To the left of the path, ﬁnd the California Nutmeg.
Deer Fern Blechnum spicant (17) Red Elderberry Sambucus racemosa var. racemosa (19) Red Alder Alnus rubra (21)
11. California Nutmeg Torreya californica
This evergreen tree has stiff, spine-tipped needles. Its aromatic
seeds resemble the unrelated common spice of the same name.
The Indians used the plant’s stiff spines as tattoo needles.
On your right, extending back into the center of the forest is a
beautiful stand of Chain Ferns.
12. Chain Ferns Woodwardia ﬁmbriata
These ferns can grow as high as six feet and have chain-like
rows of sori (clusters of spores) on both sides of the back of the
pinnae. The stems were used by Indians for making baskets,
either in their natural state, or dyed red with alder bark.
Continue walking to the right until you see the Buckthorn.
13. Buckthorn Rhamnus purshiana
This large deciduous shrub has red berries that turn black in the
autumn. The bark, sometimes called cascara sagrada, is the source
of a laxative drug that is harvested commercially in the Northwest.
14. Wild Ginger Asarum caudatum
This evergreen groundcover has distinctive heart-shaped
leaves that cover the forest ﬂoor. This plant, while not related
to commercial ginger, has a spicy aroma when crushed. In the
summer, small cup-shaped maroon ﬂowers appear under the
leaves in complete shade.
Also forming a carpet on the forest ﬂoor is Redwood Sorrel.
15. Redwood Sorrel Oxalis oregana
This evergreen groundcover has light-sensitive leaves that fold in the
sun. Pink ﬂowers grow on slender stalks in the spring and summer.
Continue to the right and proceed between the bench and the
large coast redwood to until you can see the Vine Maple.
16. Vine Maple Acer circinatum
This small shrub adds color to the forest before completely losing
its leaves in early winter.
Beneath the Vine Maple to the right of the path, see the Deer Fern.
17. Deer Fern Blechnum spicant
This fern is found near the coast from Santa Cruz to British
Columbia. The leaves stay green year round. It thrives in shady,
moist conditions among the decaying organic matter on the forest
ﬂoor. Indians use the roots of the fern for medicinal purposes.
Growing nearby is the California Rhododendron.
18. California Rhododendron Rhododendron macrophyllum
This evergreen California native grows throughout the moist
woods of the Paciﬁc northwest. Large bright pink ﬂowers cover
the shrub in late spring.
19. Red Elderberry Sambucus racemosa var. racemosa
This shrub bears clusters of small, cream-colored ﬂowers in early
spring. In late spring they ripen into scarlet, somewhat toxic
trees, plants and forest debris enrich the soil that supplies the seeds
with nutrients to encourage growth.
Redwood sprouts are young trees that grow from the roots of a
mature tree. They rely on the roots of the “parent” tree for their
start in much the same way as children rely on their parents for
support. Burls are the knobby mounds of growth tissue that are
found along the trunks of redwoods. When an older tree falls, the
burls contain all that is necessary to sprout a new tree.
These conditions have evolved over millions of years to sustain
a very dense living system, which has one of the greatest
concentrations of biomass (living matter) in the world.
Your walk today took you through an environment that is both
beautifully resilient and very fragile. This forest community deﬁnes
the Paciﬁc Coast ecology system and is in danger of being lost or
destroyed by logging, development and environmental pollution. To
learn more about the history, ecology and conservation of the Coast
Redwood community, see “The Redwood Forest,” Reed F. Noss,
editor, Island Press, 1998.
berries. Indians cut these plants back each fall so that the new
straight shoots can be cut for making arrows.
On your right is an illustration of a Family Circle.
20. Family Circle Sequoia sempervirens
If a redwood tree is destroyed by ﬁre as in this example at Muir
Woods National Monument, a family circle of trees may sprout
and mature around the stump. The new trees beneﬁt from the
established root system of the parent. They are clones of the
parent tree and share its genetic information.
Continue along the path until you see the Red Alder.
21. Red Alder Alnus rubra
This moisture-loving tree is a native of stream banks and marshy
places from Northern California to Alaska. Tassel-like, greenish-
yellow, male ﬂowers appear in clusters before the tree leafs out.
Female ﬂowers develop into small, woody cones with seeds that
attract birds. The tree grows to a height of ﬁfty feet.
Further along, notice the California Bay.
22. California Bay Umbellularia californica
This tree is native to the California coastal range, the foothills of
the Sierra Nevada, and southwestern Oregon. It thrives in deep
shade, and its lance-shaped leaves have an intensely pungent
odor. The tree is prized for its hard and beautifully marked wood.
To the right of the path, look for the Madrone.
23. Madrone Arbutus menziesii
This evergreen tree has peeling red-brown bark and a trunk that
often acquires an interesting gnarled form. In the spring it bears
small bell-shaped ﬂowers that mature into orange berries in late
Look down to notice the Dutchman’s Pipe
THE REDWOOD TRAIL
24. Dutchman’s Pipe Aristolochia californica
This vine is native to Central and Northern California. Flowers
appear in mid-winter before the leaves emerge and are shaped
like miniature pipes. In spring, look for the Pipevine Swallowtail
butterﬂies, whose caterpillars feed only on this plant.
25. Redwood Ecology
The Redwood forest community can only thrive within 45 miles of
the coast. In this area, ocean-moderated conditions protect tall trees
from prolonged frost, drying winds and ocean salt spray, and offer
foggy, wind-sheltered canyons and cool, north-facing slopes.
Depending on soil conditions, most moisture for the redwood
community is provided by the frequent Paciﬁc rain systems in winter
and by dense fog in summer. Fog condenses on the needle-like leaves
of these massive trees and drips into the ground supplying up to
45% of the trees water needs and creating moist ground conditions.
Although the root systems of the largest trees penetrate no more
than 10 – 13 feet deep, they can extend to 100 feet to take advantage
of the wet ground and forest streambeds. Rather than compete with
each other for water, the strong roots of the redwood community
form a network to hold water and help support each other.
The forest’s complex system of catching and storing water beneﬁts
companion vegetation like evergreens, oaks and chaparral. Many
species of birds and mammals also take advantage of the unique and
diverse conditions, nesting high in the canopy of the redwoods or
burrowing into the soft forest ﬂoor.
Redwoods reproduce in three ways: from seeds, from sprouts
and from burls. Redwood seeds, which form in cones along the
branches, require ﬁre for germination. When a ﬁre sweeps through
the forest, redwood trees protect themselves from burning because
of chemicals called tannins which are contained in the bark. If this
protective bark is broken by insects or animals, the ﬁre can get
inside and burn the ﬂammable part of the tree. This ensures that
only healthy trees will remain alive after a ﬁre. The ﬁres are a signal
to the seeds that conditions are right to begin sprouting. Burnt
California Bay Umbellularia californica (22) Dutchman’s Pipe Aristolochia californica (24)
This brochure made possible by a grant from the
Illustrations by Lee Boerger
Text by Fred Bové
Design by Kirsten Upson
San Francisco Botanical Garden Society
9th Avenue at Lincoln Way • San Francisco • 94122