Forest Clovers: Redwood Sorrel

When hiking in redwood forests, it’s likely that you’ve encountered redwood sorrel in the forest understory. A true shade-lover, redwood sorrel will fold its leaves when exposed to direct sunlight.

Places to See Redwood Sorrel

Cowell Circle

Henry Cowell Redwoods State Park

Redwood sorrel folds its leaves when exposed to direct sunlight.

When the leaves are in direct sunlight, they shrivel up and fold downwards within minutes. Sensitive cells in the plant detect the wavelength of light hitting it, causing the leaves to fold downwards when exposed to harsh light. This process is called nyctinasty.

Redwood sorrel’s folding is attributed to its sensitivity to bright sunlight. Because it is adapted to growing in low light conditions, intense light can damage the plant. Thus, folding its leaves is thought to protect it from harm.

To watch a time-lapse of this movement, check out this YouTube video. Please note that the plant shown is Oxalis triangularis, a different plant species in the same family as redwood sorrel.

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Redwood sorrel in bloom at Limekiln State Park in Big Sur, Ca.

Redwood sorrel is found on the West Coast of North America, from California to Canada.

It prefers understory habitats, often growing in coast redwood or Douglas fir forests beneath the shade of trees. It is one of the most common plants in the coast redwood understory.

Redwood sorrel leaves resemble clovers.

The leaves are 0.4 – 1.8 inches long. Redwood sorrel also has tiny (0.5 – 0.8 inch) flowers, which range from white to pink in color. Flowers can be seen in bloom from February to September.

Redwood sorrel is a good replacement for English ivy in a native plant garden.

Looking to make the conversion to native plants in your garden? Alternatively, are you looking for more native plants to introduce to your existing native garden? Consider the redwood sorrel. This plant grows well in shady conditions, forming a dense carpet beneath trees.

For more information on the planting and care of redwood sorrel in your garden, check out this article by S.F. Gate.

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Redwood sorrel at Henry Cowell Redwoods State Park in Santa Cruz, Ca.

Cool facts about redwood sorrel:

  • Redwood sorrel is truly adapted to shady environments, as it is able to photosynthesize in levels of light that are 1/200th of full sunlight.
  • The family name of redwood sorrels, Oxalis, is derived from the Greek word “oxys”, meaning sour. This is because the leaves of plants in this family have a sour taste.
  • Beware of eating too much of any plant in this family, as they contain oxalic acid. Oxalic acid can be toxic when consumed in large quantities.

Resources to learn more:

Hike Along Streams at Redwood Regional Park

Oakland, Ca – Just outside of the East Bay’s urban sprawl, Redwood Regional offers visitors the chance to see second and third-generation redwoods and a recovering stream habitat.

Species to Look Out For

About the Park

Oakland, Ca – Regional Park

Science Spotlight: Rainbow Trout at Redwood Regional

The rainbow trout is a native Californian fish species, originally found on the western coast of North America. They require good quality water to survive and reproduce. so they have become symbols of healthy American watersheds.

Their introduction to freshwater streams worldwide has resulted in their spread from their historical range. Rainbow trout have now spread to all continents in the world except for Antarctica. However, don’t be fooled by the expanded range – the rainbow trout is facing declines due to loss of quality habitats, pollution, and water diversion (to name a few). As a result, multiple species of steelhead (a special form of rainbow trout whose strategy is to migrate to the ocean as juveniles) are federally listed as endangered or threatened.

The rainbow trout’s freshwater stream habitat at Redwood Regional Park is threatened by erosion. The erosion, caused by heavy traffic from hikers, dogs, and bicyclists, causes accumulation of sediments and a decrease in stream water quality. These effects impact multiple species that use the stream for breeding – including rainbow trout and the “Special Concern”-listed California newt.

To do your part in restoring freshwater streams, be sure to stay on the trails and refrain from allowing pets to enter the stream.

Park History

Redwood Regional Park shares its legacy with many other Bay Area parks as a redwood forest ravaged by logging. The redwoods that remain today are second and third-generation kin to the giants that once stood at the park.

Visit the Park

Please note that there is a $5 vehicle fee to enter the park. Dogs are allowed on leashes, but an additional fee of $2 is charged per dog.

Here are some helpful resources to plan your visit:

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Visit California’s First State Park: Big Basin State Park

Boulder Creek, Ca – In 1902, Big Basin became California’s first state park. Today, it protects one of the largest continuous stretches of old-growth coast redwood south of San Francisco.

Species to Look Out For

About the Park

Boulder Creek, Ca – State Park

Science Spotlight: Keeping it “Crumb Clean” in California’s Parks

Marbled murrelets are small, robin-sized seabirds that have one very interesting quality: they build their nests high up in redwood trees. Redwood forest habitats have suffered from logging during the gold rush, which in turn has contributed to the steep declines of marbled murrelet populations.

Steller’s Jays and other avian predators have been shown to negatively impact marbled murrelet populations by eating their eggs and young, according to a study at Redwood National and State Parks.

Steller’s jays are crested blue and black birds commonly found at campgrounds, attracted there by food leftover from humans. The high jay density is thought to increase  the chances of Steller’s jays finding and predating the nests of marbled murrelets.

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A common sign at campgrounds, featuring a Steller’s jay and a warning to clean up all traces of food. Source: Save the Redwoods League.

Public education programs, such as the “Crumb Clean” initiative depicted above, warn people that food waste has the potential to impact marbled murrelet populations by attracting their predators.

The moral of the story? Be careful of leaving any trace on your hikes – even a crumb can make a difference!

For more information on marbled murrelets and Steller’s jays, check out the Bay Area Naturalist article “Logging, Crumbs, and Lost Fish: The Story of the Marbled Murrelet“.

Park History

In 1902, Big Basin State Park became the first state park established in California. Its land protects mostly redwood forest and is home to the largest continuous stretch of old-growth redwoods south of San Francisco. Scientists estimate that the older trees in the park range from 1,000 to 2,500 years old.

Prior to the arrival of Europeans, Native Americans inhabited the park’s land for thousands of years. Evidence of the Native American’s land use can be seen in the bowl-like depressions in rocks along the trail. These depressions were used by the Ohlone people to grind seeds and acorns into flour.

In the midst of logging in the late 1800’s, a small group of citizens formed the Sempervirens Club (sempervirens being the species name of coast redwoods). They spurred a movement amongst California’s citizens, which resulted in the creation of a bill to protect the park area. The park is currently over 18,000 acres and growing.

Visit the Park

Please note that there is a $10 vehicle fee at the park. Dogs are not allowed on trails, but are allowed on leashes at picnic areas.

Here are some helpful resources to plan your visit:

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Enjoy the Stillness of Redwood Stands at Purisima Creek Redwoods Preserve

Half Moon Bay, Ca – Purisima Creek Redwoods Preserve offers rich history and wildlife. Learn about its recovery from logging and its amphibian resident, the California newt.

Species to Look Out For

About the Park

Half Moon Bay, Ca – Nature Preserve

Science Spotlight: California Newts at Purisima Creek

Dan and I encountered our first California newt while hiking alongside Purisima Creek. We had been on the lookout for newts for the past few weeks, so you can only imagine our excitement when seeing a bright orange amphibian crossing our path.

California newts are found along the coast and mountain ranges of California, from Mendocino County to San Diego County. They are endemic to California, meaning that they are not found outside the state. They live a dual lifestyle, spending half of their time in water and the other half on land.

California newts are listed by the California Department of Fish & Wildlife as a “Species of Special Concern”. Ponds that they use for breeding and maturation have been lost to development. Fish, crayfish, and bullfrogs introduced to California’s freshwater areas threaten populations by eating California newt eggs and young.

Look out for California newts during their migration to their breeding grounds, which usually coincides with the first rains in the fall. If you see one of these bright creatures along the trail, be sure to not pick them up! Not only could you disturb them, but their skin is also loaded with a neurotoxin. The toxin, tetrodotoxin, is found in all species in their genus. It is also found in pufferfish.

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A California newt near the creek’s edge at Purisima Creek Redwoods Preserve.

Park History

Prior to its status as a nature preserve, the Purisima Creek area housed seven saw mills supplying coast redwood lumber to the booming gold rush population in the San Francisco Bay Area. The entire preserve was cleared of trees that were large and intact enough for lumber.

The Save-the-Redwoods League gifted $2 million to the Midpeninsula Regional Open Space, which allowed for the establishment of the park. Purisima Creek Redwoods Preserve offers 4,711 acres of recovering coast redwood forest, creeks, and a canyon.

Visit the Park

Please note that there is no entrance fee to enter the park. Dogs are not allowed.

Here are some helpful resources to help plan your visit:

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Towering Trees: The Coast Redwood

Coast redwoods are the tallest trees on Earth – and they also only live in the Bay Area.

Places to See Coast Redwoods

Coast redwoods are the tallest trees on Earth.

Coast redwoods grow to heights of over 379 feet – as tall as a 38-floor skyscraper. They can also grow to widths of 26 feet in diameter.

Coast redwoods get their name from the rich color of their bark.

True to their name, these giants have beautiful reddish-colored bark. The rich color is due to high contents of tannins, a chemical which helps them repel damage from insects. Their bark is also especially thick to help protect them from forest fires, which seasonally occur in California.

Coast redwoods live for thousands of years.

Coast redwoods are known to live over 2,000 years. They are an ancient species that dates back to the Jurassic Period over 200 million years ago.

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Hiker Mary Gibbs admires coast redwoods at Big Basin State Park.

Coast redwoods only grow in one place on Earth: the coast of Northern California to Southern Oregon.

Coast redwoods can only be found on the coast of Northern California up into Oregon. In their range, they do not extend more than 50 miles inland. The heavy rains in the winter provide them with plenty of water. In the dryer months, the coastal fog provides much-needed moisture to the redwoods.

Millions of years ago, there used to be many species of redwood tree in the Northern Hemisphere. Today, only three species have survived the millions of years of changes on Earth: the coast redwood, the giant sequoia, and the dawn redwood. 2 of the 3 remaining species (coast redwood and giant sequoia) can be found in California, whereas the dawn redwood can be found in China.

Only 5% of the original old-growth trees survived logging along California’s coast.

The California Gold Rush in 1848 brought about a huge population boom – and with the rise of the human population came a rise in demand for lumber. Settlers looked to California’s coast for sources of wood, decimating stands of coast redwoods in the process. Extensive logging has reduced the population of old-growth trees (trees that have survived a prolonged period of time without disturbance) to 5% of its original size.

Cool facts about coast redwood trees:

  • The tallest known coast redwood is named Hyperion, who stands at 379 feet tall.
  • Coast redwoods have very shallow root systems relative to the heights that they reach. To provide stability in the face of strong winds, they grow their roots outwards and intertwine them with neighboring trees.

Resources to learn more:

Nature’s Majesty: The Giant Sequoia

California is home to the largest tree on the planet – a giant sequoia named the General Sherman Tree. Learn about this massive tree species, its old age, and how it inspired the National Park Service logo.

Giant sequoias are the largest trees on Earth.

Giant sequoias are truly giants – they can grow to heights of about 300 feet and their trunks can reach diameters of about 30 feet. While some tree species can match the giant sequoia by either height or diameter, no other species can beat both. Because of this, giant sequoias grow to be the world’s largest trees.

Giant sequoias stop growing in height over time; however, they are always growing around the trunk. The largest tree on the planet, General Sherman, is a giant sequoia at Sequoia National Park. Each year, it grows enough wood around its trunk to be equivalent to a large tree of a different species.

Giant sequoias live to be thousands of years old.

Giant sequoias live for thousands of years. The oldest giant sequoia is estimated to be 3,210 years old.

To age a giant sequoia, scientists count the tree rings from an intact trunk of a fallen tree. Using the information from the trunk, scientists can then estimate the ages of standing trees that are a similar size and that grew in a similar environment.

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Giant sequoia in King’s Canyon National Park

Giant sequoias are only found in California.

Giant sequoias have a very restricted range, meaning that they only grow in a small area on Earth. Giant sequoias are only found on the western side of the Sierra Nevada mountains in California, along a short stretch of about 250 miles. They grow at elevations of 4,000 to 8,000 feet.

Giant sequoia seeds have a one in a billion chance of becoming an adult tree.

Giant sequoia seeds are only about as big as a pinhead, enclosed in a small, egg-shaped cone. Trees will not produce large amounts of seeds until they are several hundred years old. Reproducing giant sequoia trees will deposit millions of seeds each year; however, because of harsh growing conditions, there is a one in a billion chance that the seedling will grow into a mature tree.

Giant sequoias, like all other species, are subject to the effects of climate change.

It is estimated that 92% of the larger giant sequoia trees are protected by public agencies, namely the National Parks and National Forests. Yet despite this federal protection, parks can no longer guarantee the safety of the trees when faced with the consequences of climate change.

Giant sequoias only live on the western slope of the Sierra Nevada mountains in California. This restricted range puts them in danger as climate change threatens our planet. Climate change may cause the area to be too hot or too dry for the trees, putting the species at risk.

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Giant Sequoias looking down at the parking lot in King’s Canyon National Park

Cool facts about giant sequoias:

  • It is estimated that there are only about 20,000 giant sequoias alive that have diameters greater than 10 feet.
  • The roots of mature giant sequoias stretch out over 100 feet in every direction.
  • Giant sequoia bark is thick and contains little sap to help protect it from fires.
  • Giant sequoias are on the U.S. National Park emblem. This is because 3 of the 4 first National Parks created protected giant sequoias.

Resources to learn more: