Youth Education Program
of San Francisco Botanical Garden Society
Redwood Trail
Introduction to Redwoods
THE ENDURING GIANTS
The beauty, majestic size, and survival power of the redwoods have long inspired poets
and artists, and delighted people who love natural beauty. Redwoods are the world’s
largest living things, and live to be among the oldest as well. Trees can tower over
35-story buildings and weigh as much as 800 buses! Living for centuries, some trees
standing in California right now were tiny seedlings when the Egyptians ruled, and were
already
grown trees
when George Washington became president. As redwoods evolved
Basic
Information
over the centuries to adapt to life in a changing world, they developed the ability to
resist fire, disease, and pests, and to alter their own environment. The story behind these
beautiful living treasures is as remarkable as the trees themselves.
LIVING FOSSILS
Redwoods are a living link to our past, for the history of this ancient race of trees began
over 160 million years ago. When dinosaurs roamed the land, most of the northern half
of the planet was covered with lush redwood forests. These primeval forests flourished
for millenia until gradual changes in the climate left the land covered with sheets of ice.
Of the dozens of species of redwoods that once grew, the three species we’ll explore in
our walks are those that survived the cold of the glacial age - the coast redwood, the
giant sequoia, and the dawn redwood. Today redwood forests cover less than 1% of
their original range, growing naturally only along a narrow strip of land on the coasts of
California and Oregon, on the western slopes of the Sierra Nevada, and in one remote
valley in China.
Even confined to this small territory the redwoods played an important role in the
history of California. For centuries only the Indians knew of the vast coastal redwood
forests. They respected and worshipped the trees and used the wood in many ways.
Bark and root were shredded and used for clothing and baskets. Tree trunks were split
and used for dwellings and sweathouses, and large logs were hollowed out and
fashioned into canoes.
When the first European explorers arrived the sailors used the enormous redwoods
growing around the San Francisco bay as landmarks to guide them. A group of Spanish
explorers led by Don Gaspar de Portola were the first to describe and document the
magnificent redwood forests in 1769. Awed by the size and beauty of the trees they
named them “palos colorados” – the red tree. In 1874, the redwoods were given their
official Latin name, Sequoia sempervirens – ‘Sequoia’ from the name of the Cherokee
Indian who created a written language for his people (Sequoya), and ‘sempervirens’
meaning ever-green.
As the Spanish moved into California they used the redwood trees to build their
missions. But surprisingly, the first Europeans to extensively log and use the redwoods
were Russian trappers who came to the northern coast of California in the early 1800’s
to hunt for otter. They settled at the mouth of the Russian River and built a fort, now
named Fort Ross. At 160 years old, this fort is the oldest wooden building in the West
and a testament to the durability of the redwood.
Gradually other Europeans arrived in California. As settlers, traders, and gold miners
began to build their homes in California and the demand for lumber soared. With its
beauty, strength, and durability the wood of the redwood was in great demand. Mills to
log the redwood forests and railroads to transport the lumber sprang up all along the
coast and a new industry was born.
The awesome size and cathedral-like stillness of the vast forests gave rise to many
myths, legends, and folktales about the redwoods. The Indians drank the sap of the
redwood hoping to capture some of the redwood’s magical powers of strength and
endurance. Some believed that the redwoods were strong warriors turned into trees.
European settlers believed that gnomes made the redwoods their homes as they helped
to care for the creatures of the forest. Lumbermen told tales about Paul Bunyan’s visit to
the redwoods and his adventures clearing land for settlers.
THE FAMILY OF REDWOODS
Taxonomically speaking, redwoods form a distinct subfamily within the cypress family,
and the three species include two that are native to California and one which is native to
China.
Coast Redwood (Sequoia sempervirens – “evergreen sequoia”)
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The world’s tallest tree, the coast redwood can grow to at least 380 feet – that is over 2
½ times the height of the Statue of Liberty! The oldest known tree has been alive for
2,200 years. The coast redwood is found only in the coastal fog belt, a narrow strip of
land about 20 miles wide that extends for 500 miles along the coastal mountains of
central and northern California and southwest Oregon. The San Francisco Bay area is
lucky to have great stands of these living treasures.
Sequoia (Sequoiadendron giganteum – “giant sequoia”)
Imagine a tree so big that its trunk alone could provide the wood for 40 five-room
houses! While not as tall as the coast redwood, the giant sequoia is the most massive of
all living things. One tree named General Sherman weighs 12 million pounds – the same
as a small steamship. They can grow to be 300 feet tall, and they can live to be an
astonishing 3,600 years old. These massive giants grow only in one very small area on
the western slopes of California’s Sierra Nevada mountains. Because their brittle wood
was not suitable for logging, over 90% of these magnificent trees are now protected in
state and federal parks.
Dawn Redwood (Metasequoia glyptostroboides – “akin to sequoia”)
Thought to have been extinct for over 20 million years, the survival of this redwood was
a wonderful surprise for botanists. It was found in 1944 growing only in one very remote
valley in the interior of China. At one time it had been a dominant tree in the northern
hemisphere. This smaller cousin of the redwoods grows to at least 150 feet and may live
to be about 600 years old. Unlike the other redwoods this lovely tree is deciduous,
losing its needle-like leaves each fall. While it still grows naturally only in its secluded
valley in China, these trees have been successfully cultivated in gardens in many
countries around the world.
THE REALM OF THE COAST REDWOOD
Coast redwoods are strong and hardy trees, but they do need a special type of climate
to survive and grow. They need a lot of moisture all year-round and protection from
strong winds. California’s coastal range provides a perfect habitat with its mild
temperatures, heavy rains and cooling fog.
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Coast redwood are very thirsty trees and need from 40” to 100” of rain a year. More
than half of the redwood’s massive weight is water. They can hold more water in their
trunks than any other tree – as much as 8,000 gallons of water! When the rainy season
stops, fog provides them with the moisture they need and slows the evaporation of
water from their leaves. These amazing trees comb moisture from the air as fog droplets
condense onto their needles and drip to the ground, adding literally feet of annual
precipitation in some cases.
Given good soil, sunlight, and the right amount of moisture redwoods can grow 200 feet
in less than a century.
SURVIVAL OF THE FITTEST
Each part of a coast redwood tree reveals a special trait or characteristic that enables it
to survive. For example, the beautiful red bark of the redwood protects the tree in many
ways. The soft, fibrous bark grows up to a foot thick, providing insulation that shields
the tree from fire. In addition, the bark and wood contain very little of the resins that
make other trees so flammable. Even coast redwoods that have been partly burned have
a remarkable ability to survive and heal over their scars. Another important adaptation is
a strong, acidic chemical in the bark and wood of the tree called tannin. It is the tannin
that gives the redwood its beautiful reddish color and helps it resist disease, fungus, and
insects.
For such enormous trees you might imagine that the roots must grow down for miles.
But surprisingly, the coast redwood’s roots extend no deeper than the height of an
average man! Their shallow root system only grows from 6 to 8 feet deep to take
advantage of the water available near the soil’s surface, but the roots extend outward as
much as 100 feet. Since redwoods don’t have a long, deep taproot like other trees,
balance is critical. Strong winds are a dangerous enemy and a winter storm can topple
the tallest giants. If a tree begins to lean, it can balance itself by growing heavy limbs to
pull the weight back and by forming more wood on the side that leans to brace itself.
The leaves of the coast redwood are also wonderfully adapted for survival. Like other
trees, the leaves of the redwood manufacture food for the tree through photosynthesis.
But they are also specially adapted to catch moisture from rain and fog, and to release
moisture from their undersides and drip it down onto the roots. At the top of the tree
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the needles grow flat along the stem, but on the parts of the tree that grow in shade the
needles open in broad sprays so that they can catch more light. Each spray of needles is
divided into sections, with each section representing one year’s growth. Long segments
indicate a good growing season for the tree, while short segments indicate a dry year
with less growth.
Another important adaptation that helps the coast redwood to survive is its ability to
reproduce in two ways, by seed and by sprouting.
It is hard to believe but a redwood can grow from a tiny seed weighing 1/800th of an
ounce – less than a small feather! The seeds are held in small cones that can hold from
50 to 150 seeds. Each tree grows both male and female cones. Pollen grains from the
male cones drift down to fertilize the seeds in the female cones, and the seeds begin to
grow. When they are mature, billions of seeds are released from the cones each autumn.
These tiny seeds must find exposed soil and a patch of sunlight, and must be able to
survive insects, animals, fire, and flood if they are to grow. Fewer than one in a million
seeds survive to become a mature redwood.
Since so few seeds survive, the coast redwood’s ability to sprout is its primary means of
reproduction. New redwood trees sprout from fallen trees, from stumps, and from the
bases of living trees. Even when a tree falls or is destroyed by fire its life doesn’t end.
Sprouts emerge from the stump, from the old root system, and from gnarled masses of
dormant buds called burls. In redwood forests you will often see “fairy circles” – a circle
of trees which began as young sprouts rising from the base of a tree that no longer
stands. New forest plants often take root in the stumps of fallen redwood trees where
the old wood provides moisture and nutrients. While redwood sprouts must still
compete for sunlight and moisture, they are usually more successful than seeds because
they are growing from an already developed root system.
RECIPE FOR A REDWOOD FOREST
Every coast redwood forest supports a great variety of life. Coast redwoods are only one
part of a community of plants and animals that rely on each other for survival. If you
look closely, you can see that a redwood forest is really made up of several layers of
plants from the low growing groundcovers to the high canopy formed by the crowns of
the trees. Each layer is home to plants and animals that have adapted to living in the
redwood forest ecosystem – many of them unique to the redwood forest.
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Duff – This soft carpet of woody debris and leaf litter covers the forest floor, holds
moisture, and provides homes for animals and insects that break down dead plant and
animal materials, converting it into nutrient rich soil.
Ground cover - Here in the deep soft shade of the forest floor, redwood sorrel and wild
ginger creep along forming lush green carpets. Mushrooms, molds, and fungi grow
from rotting logs. Beautiful wildflowers like columbine, bleeding heart, and trillium grow
amidst clumps of ferns and primitive looking horsetails. Growing near water are skunk
cabbage and colonies of stream orchids. Many of the plants that grow in the shade
beneath the redwoods have developed broad, flat leaves that help them catch as much
sunlight as possible. Snakes, banana slugs, chipmunks and many other tiny creatures
make their homes here.
Shrubs – Many woody plants grow amidst the redwoods, especially where openings in
the forest give them additional light. They offer protection and food for birds and
animals like deer and Steller’s jays. Many of the shrubs produce berries, such as
evergreen huckleberry, thimbleberry, and red elderberry. Others grace the forests with
their showy flowers like the rhododendron and azalea.
Understory – Here many other trees grow to share the redwood forest. Young redwoods
share the woods with Douglas fir, bigleaf maple, tanbark oak, California bay and coast
hemlock. Many of the trees grow only on the edges of the forest or in large gaps where
redwoods have fallen, where they can find enough sunlight.
Canopy – The top branches and leaves of the redwoods form a canopy high above the
forest, shading the forest floor and keeping the redwood roots moist and cool. But this
high zone is home to more than just birds, and in fact, an entire ecosystem has
developed high up in the redwoods, including plants and animals that live and grow on
and among the branches.
THE ENDURING GIANTS
In the 200 years that our ‘modern civilization’ has known about coast redwoods, over
85% of the trees have been logged. After surviving for thousands of years California’s
redwoods were suddenly in danger of disappearing. It wasn’t until 1901 that the first
area for protected redwoods was set aside. Because of the hard work and efforts of
individuals like John Muir and conservation groups like the Save the Redwoods League,
California now has 31 state redwood parks.
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Most of our nation’s redwoods are here in California. Only a tiny percentage of ‘old
growth’ redwood forests remain – forests which have never been logged and so have
the greatest variety of plants and animals and the oldest trees. These old growth forests
hold the secrets of a complex community with the ability to change and survive over
long periods of time. Today the timber industry, environmentalists, and lawmakers are
trying to find a balance between the need for jobs that logging provides and the
importance of preserving these amazing trees.
An Iroquois Indian law says: “In our every deliberation we must consider the impact of
our decision on the next seven generations.” It is up to us to make sure that these
magnificent national treasures are here to inspire future generations, and that there are
places where the cycles and rhythms of the forest remain undisturbed. As we struggle to
deal with this complex issue, perhaps the redwoods can help us learn how to live in
balance with each other and our world.
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