The Redwood Trail San Francisco Botanical Garden At Strybing Arboretum


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The Redwood Trail San Francisco Botanical Garden At Strybing Arboretum

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The Redwood Trail San Francisco Botanical Garden At Strybing Arboretum

  1. 1. 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, and sugar-scoop. 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 California Hazelnut. 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
  2. 2. 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. Redwood Conservation 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 summer. Look down to notice the Dutchman’s Pipe THE REDWOOD TRAIL SAN FRANCISCO BOTANICAL GARDEN AT STRYBING ARBORETUM 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) Redwood Trail This brochure made possible by a grant from the Save-the-Redwoods League Thank you Mia Monroe 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