The Real Dirt Blog - Agriculture and Natural Resources Blogs

Local Trees: The Pacific Madrone – Rare in Lower Bidwell Park

Published on: May 17, 2019

By Laura Lukes, UC Master Gardener of Butte County, May 17, 2019

A beautiful tree sits on the north side of Little Chico Creek, shading the picnic table at site #34 in Lower Bidwell Park. Its thick, smooth lower branches are perfect for climbing, and its form is both rounder and more symmetrical than its relatives at higher elevations. And its occurrence at our low altitude (elevation 197 feet) is rare.

Madrone in Lower Bidwell Park by Laura Lukes

Arbutus menziesii, a broadleaf evergreen hardwood tree, is best known as Pacific madrone. It is most often found along Puget Sound, and in the Oregon and California coast ranges; it is also scattered on the western slopes of the Sierra Nevada and Cascade mountain ranges. Its favorite habitats in southwestern Oregon and northern California are dry foothills, wooded slopes, and canyons. In California, madrone grows best at elevations between 300 and 4,000 feet. If you've driven State Route 20 between Willits and the coast, you've seen these stately trees reaching above the coast redwood and mixed-evergreen forest canopy on the steeper slopes.

Captain George Vancouver of the British Royal Navy commanded a voyage of exploration and diplomacy from 1791 to 1795 which circumnavigated the globe and made contact with five continents. Madrone's species name honors the Scottish surgeon, botanist and naturalist, Archibald Menzies, who noted this tree during Vancouver's voyage of exploration. Menzies, who spent many years at sea serving with the Royal Navy and on private merchant ships, recognized its similarity to the European arbutus, A. unedo, which today is a popular landscape tree in Chico. Its red fruits are shaped like strawberries, and in fact the Spanish word madroño translates as “strawberry tree.” Other common names include madroa, madroo, madroña, and bearberry.

Pacific madrones are usually tall and slender, reaching above the surrounding forest canopy by mindgrow from Schwalmtal, Deutschland

While all parts of the Pacific madrone are remarkable, its best-known characteristic is that it freely peels its outer bark. Once this skin-like outer layer is shed, the remaining bark is smooth and polished, with a distinctive reddish color. Young bark darkens to a deep red with age; younger stems can range from green to chartreuse, and young trunks are frequently orange. Older portions of the bark become a dark, brownish red. The deep color of the bark contrasts nicely with the tree's large, glossy, dark green foliage. In spring, sprays of small, bell-shaped white flowers adorn the branches, giving way to red berries in the autumn months.

The madrone has evolved an effective method of seed regeneration: each berry contains between three and 30 seeds, and when the berries dry they develop hooked barbs that can latch onto the fur and skin of passing mammals, hitching a ride to colonize new locations.

The Pacific madrone ranges in height from about 33 to 82 feet but can reach up to 100 feet or more in ideal conditions. In those perfect conditions, it can reach a thickness of 5 to 8 feet at the trunk, much like an oak tree. Ideal conditions include a sunny site such as a south or west facing slope with soil that is well drained and lime free.

The largest known specimen of Pacific madrone lived in Joshua Creek Canyon Ecological Reserve on the Big Sur Coast. At least 125 feet tall and more than 25 feet in circumference, and listed on the American Forests National Big Tree list, it sadly was severely burned in the 2016 Soberanes Fire.

Madrone in Lower Bidwell Park. Low, horizontal branches are tempting to climb by Laura Lukes

Surviving Drought and Fire: At the base of its trunk, the Pacific madrone has a woody, globe-shaped, regenerative organ known as a burl. This structure is a peculiar adaptation to its forest habitat, which historically experienced regular burns at intervals averaging between 10 and 35 years. The Pacific madrone is susceptible to fire, but also relies on fire to regenerate. Its low resistance to fire is due to its thin bark. Conversely, repeated top-kill by fire encourages burl development, enhancing Pacific madrone survival - the burl serves as a source of stored carbohydrates for prolific postfire sprouts. These rise from dormant buds on the burl, and initially grow rapidly after a fire.

A massive, wide-spreading root system increases its ability to withstand summer drought. In fact, the tree prefers dry, well-draining soils and does not tolerate direct watering during the summer months. Once established, Pacific madrone is windfirm, drought enduring, and somewhat tolerant of wet, freezing conditions.

Burl at the base of Pacific madrone by Thewellman Commons Wikimedia

Native American Uses: The Concow tribe calls the tree dis-tā'-tsi or kou-wät′-chu. Native Americans sometimes ate the berries, but were more likely to make them into a type of cider, or chewed them to cleanse their mouths, since the berries' high tannin content makes them astringent. Madrone berries were used in necklaces and other decorations, and as bait for fishing. Tea made from the bark and leaves was used to treat stomach aches, cramps, skin ailments, and sore throats. The wood was used to make implements and it was particularly useful as firewood; its density and hardness ensures it burns long and hot -- even better than oak.

Pacific madrone is a particularly beautiful tree, with its reddish curved trunks supporting a broad, spreading crown of deep green leaves. It is most often seen as a single specimen tree displaying its finery among the more common Douglas fir and tanoak. It is currently declining throughout most of its range, unfortunately due to 100 years of forest fire control and urban development in its native habitat. We are lucky to have our lovely, rare specimen in Lower Bidwell Park.

For more information on gardening in our area, visit the UC Butte County Master Gardener webpage at: http://ucanr.edu/sites/bcmg/. If you have a gardening question or problem, call our Hotline at (530) 538-720l or email http://mgbutte@ucanr.edu.

Tags: Arbutus menziesii (1), Butte County Master Gardener (38), Pacific madrone (1)

Focus Area Tags: Yard & Garden

Be on the Lookout for the Asian Citrus Psyllid

Published on: May 3, 2019

By Jeanette Alosi, UC Master Gardener of Butte County, May 3, 2019

Butte County is known for its delicious citrus. Mandarins are grown commercially in our “banana belt” foothills, and residents in the valley can enjoy citrus grown in their own gardens. However, a tiny flying insect the size of an aphid poses a grave threat to our local citrus. This insect is the Asian citrus psyllid (ACP), a vector for a dangerous and fatal bacterium (Candidatus Liberibacter asiaticus) that causes Huanglongbing (HLB) disease, previously known as Citrus Greening disease. HLB has devastated the Florida citrus industry and has been found in Southern California. Recently the Asian citrus psyllid itself (but not HLB) was found in Sacramento, just 100 miles south.

Map of ACP and HLB spread by ANR

The Asian citrus psyllid and HLB originated in eastern Asia or in the Indian subcontinent and has spread rapidly throughout the world. In 1998 the psyllid along with HLB disease was found in Florida. Within 3 years HLB had infected most citrus-growing regions in Florida. This infection was traced to an infested shipment of orange jasmine (Murraya paniculate) in the family Rutaceae, the same family as citrus. Other susceptible ornamentals in this family include Indian curry leaf, calamondin and mock orange.

ACP was first detected in Southern California in 2008, followed by HLB detection in 2012. The psyllid has expanded into the Central Valley, the Central Coast and as far north as the Bay Area and Sacramento. So far there has been no detection of HLB disease outside of Southern California.

There is no cure for HLB, which can kill a tree in 5 to 8 years. Because HLB can only be spread via the ACP, the key to prevent HLB is monitoring for, and controlling, the psyllid.

ACP adult and nymphs with white tubules by ANR

Identification of the Asian Citrus Psyllid (ACP): The winged adult ACP is about the size of an aphid. It has a pointy front end, red eyes, and short antennae. It feeds at a unique 45-degree angle, with its head down and its back end in the air.

Adults only live for a few months but can lay several hundred tiny, yellow-orange, almond-shaped eggs in fresh new citrus growth. The tiny wingless nymphs hatch from the eggs and are yellow, orange or brown. They molt 4 times, increasing in size each time.

ACP nymphs only feed on new citrus shoots and leaves. As they feed, a toxin is injected causing leaves to twist and curl, sometimes killing new shoots. Nymphs also produce excess sap or honeydew which promotes the growth of sooty mold. To direct the honeydew away from their bodies, they produce waxy, white tubules. The tubules are unique to the nymphs and are easily identified. Other insects such as aphids can cause these same symptoms, but they do not produce tubules nor are they a vector for the bacterium causing HLB.

Irregular blotchy and yellowing of leaves by ANR

Symptoms of HLB Disease. Early symptoms of HLB cause the leaves to yellow on a particular limb or section of the tree. The yellowing appears asymmetrical and blotchy or mottled. (Although nitrogen or zinc deficiencies can also cause yellowing, they follow a symmetrical yellowing pattern). Over time, fruit on an HLB-infected tree becomes smaller and juice becomes bitter. The citrus fruit itself may stay partially green, which is why HLB was first called “citrus greening disease.” Fruit may also appear misshapen. The foliage becomes sparser with twig and limb dieback, and the tree eventually dies. Even though infected, symptoms may be undetected for a few years, allowing ACP to spread the disease unless the insect is controlled.

Now that the ACP is firmly established in California, the Department of Food and Agriculture (CDFA) is tracking its distribution through the use of yellow sticky traps in commercial and residential areas. ACP quarantine zones are being used to restrict the transport of citrus trees and the spread of the psyllid. Biological controls using predators and parasites that feed on the ACP are being used to help control (but not eradicate) the ACP.

The University of California Division of Agricultural and Natural Resources has an updated map on the spread of the ACP and HLB you can find at https://tinyurl.com/y4lchxk7. A California regulation and quarantine boundary map can be found at http://tinyurl.com/y3ftxzzu.

How you can help. Monitoring citrus for the presence of the ACP and symptoms of HLB is key for controlling this fatal disease. Inspect your citrus any time there is a flush of newly developing leaves; especially in springtime (now), and later on the fall flush. Like aphids, psyllids feed on new, developing leaves. Look for evidence of the ACP in new growth by checking for:

Adult psyllids feeding, head down and rear end in the air (a 45 degree angle)
Twisted or notched leaves in new growth
Sticky honeydew and black sooty mold
Nymphs that produce waxy, white tubules
Tiny, yellow, almond-shaped eggs

Citrus leaves distorted and malformed by psyllid feeding by ANR

If possible, use a magnifying hand lens or take a photo and then enlarge it to help identify the tiny eggs, nymphs and psyllids. Yellow sticky traps for monitoring the presence of psyllids can also be purchased.

Control ants that like to “farm” the psyllid honeydew to feed their young. Ants will protect the psyllids from their natural enemies such as parasites and other predators. Only purchase citrus trees from reputable sources and DO NOT transport citrus trees, fruit, or cuttings from areas known to harbor the psyllid.

If you suspect the presence of the ACP or any evidence of HLB disease, immediately contact the Butte County Agricultural Commissioner's Office (530-538-7381), or the CDFA Citrus Threat hotline (800-491-1899).

Sources for more information include:

The UC IPM Publication for ACP and HLB Disease at http://tinyurl.com/yy6jtgy9

California Department of Food and Agriculture at https://www.cdfa.ca.gov/plant/acp/

Citrus Pest & Disease Prevention Program at http://californiacitrusthreat.org/

For more information on gardening in our area, visit the Butte County Master Gardener web page at: http://ucanr.edu/sites/bcmg/. If you have a gardening question or problem, call our Hotline at (530) 538-720l or email http://mgbutte@ucanr.edu.

All photos are from the University of California Division of Agriculture and Natural Resources (ANR).

ACP adult feeding with back end in the air by ANR

Fruits is small, hard and misshapen. Such symptoms may not show up for a year or more, ANR

ACP feeding on new citrus leaves by ANR

Nymphs with honeydew tubules by ANR

Tags: ACP (1), Asian Citrus Psyllid (1), Butte County Master Gardener (38), citrus disease (1), citrus greening (1), HLB disease (1)

Focus Area Tags: Yard & Garden

Just Don’t Call It Senior Gardening!

Published on: April 19, 2019

By Laura Lukes, UC Master Gardener of Butte County, April 19, 2019

“Gardening becomes increasingly difficult as we age, yet the garden beckons as strongly as ever,” notes Butte County Master Gardener Kay Perkins. Our bodies become less limber and agile, and more prone to injury, which makes tasks such as pulling weeds, pushing wheel-barrows, digging holes, pruning, hauling, and moving heavy objects ever more challenging with advancing years.

Moonshine yarrow with deer grass in background by Laura Kling

But the idea of voluntarily giving up the passion and pleasure of working in the garden is unthinkable for most gardeners. With that in mind, the UC Master Gardeners of Butte County recently held a workshop on how to stay healthy and active in the garden, offering practical advice that can help transform daunting chores into sustainable activities. Workshop leaders Kay Perkins and Marsha Ebert shared information about landscape strategies, plant choices, labor-saving techniques, and cleverly-designed tools.

The workshop topics were summarized from a book by Sydney Eddison, Gardening for a Lifetime: How to Garden Wiser as You Grow Older. Eddison is the author of six previous books on gardening, and was awarded the National Garden Clubs, Inc.'s Award of Excellence in 2010.

For over 50 years, Eddison (who was born in 1932) was an aficionado of time-consuming gardening choices: "It took a great deal of effort to make my garden as high-maintenance as it is….That was the point of it all” she writes. Then a bothersome hip replacement put a damper on her garden activities, one of which was "digging great big holes and moving plants around all the time.” Refusing to give up the gardening she loved, she began researching low-maintenance garden techniques. Those discussed at the workshop are explained below. A list of suggested tools and plants can be found at the end of this article.

Rethinking Perennial Borders: Eddison once designed, planted, and maintained huge perennial borders. Perennials are notoriously labor intensive, often demanding year-round attention, including staking, deadheading, pruning, dividing, and neatening and tidying. Granted, they offer enormous rewards in terms of color and texture, and add overall interest to the landscape. Eddison argues that shrubs can play the same role in the garden, with infinitely less trouble. Shrubs offer the same or more value, for less work.

Choose compact or dwarf varieties of popular shrubs (such as buddleia) that need pruning only one or two times a year. Shrubs that produce berries add a splash of bright color to gray winter days, and provide a source of food to overwintering and migrating bird species. Eddison is a fan of conifers because they offer year-round color and variegated foliage texture, and also add structural interest in the form of cones, globes, and mounds. But choose wisely and think carefully before planting shrubs as they are more difficult to move than perennials.

Daylily by Brent McGhie

Perennials that do make the cut for a lower-maintenance garden border should be held to a high standard of good behavior. They should be able to retain attractive form and color throughout most of the seasons, particularly our hot, dry summers. Well-behaved perennials must maintain a tidy habit, with no flopping or sprawling. If any plant, be it shrub or perennial, tends to dominate your time, you can reduce the number of them you allow in the garden, or find a replacement.

List, list, list: Making lists saves time, reduces aggravation, and increases organization and efficiency. Take the time to develop a Master List and a Daily List. The Master List should contain all garden tasks, large or small, organized by season and species (such as tree, shrub, or perennial), prioritized by importance. Your list may seem daunting and impossibly long at first, but Eddison promises that you will be surprised by how many of these tasks you will be able to accomplish. Nothing beats the satisfaction of crossing a task off the list for that season.

The Daily List is developed from the Master List and should be realistic for the time you can allot to the garden on any given day, and for your abilities. This list should also indicate if the task is essential or aesthetic in nature. These lists can help you keep from getting distracted or pulled in different directions by the garden's demands. If you are lucky enough to have a helper in for the day, a list for your helper will save him or her time.

Hire Helpers: The wisdom of age tells you that those days of “I can do it all without help” are over. Start by determining what kind of help you need (and this will change over time). Do you need help periodically with large jobs, on a weekly, monthly, or seasonal schedule, or would you like to be able to call on someone as needed? Do you need an experienced professional, or someone to whom you can teach the necessary skills? Places to find garden helpers include: horticultural programs at high schools, vocational schools, and community colleges; referrals from fellow gardeners; and contacts from local nurseries. Be sure to be clear about what you want your helper to do. And make sure you are realistic in your expectations, the number of hours you think tasks will take, and what you are willing to pay.

Moonshine yarrow by Brent McGhie

Speaking of Being Realistic: Gardens are only perfect in catalogs and (perhaps) for a short and finite window of time in our own yards. Learn to accept imperfections, and understand that plants are always in a state of “becoming.” Leave some dead leaves under shrubs to serve as mulch that will enrich your soil. Allow grass clippings to remain on the lawn, to sink in and feed the grass. By the way, whatever it is, if it's kept short and green – viola! - it's a lawn.

Realize which plants have grown beyond your ability to manage. Decide whether to 1) continue to invest time and money into them; 2) give them a brutal pruning to see if that revives them; or 3) remove and replace them. The hardest friends to remove are the old landscape trees which have contributed shade and beauty to the garden over many years. If one must go, don't be too quick to replace it – you may find the increased sun allows new landscape opportunities and that you enjoy the newly-opened space.

Container Gardens: Gardening in attractive containers of varying shapes and sizes is an excellent choice for yards with poor soil, and for those gardeners with increasingly limited mobility and/or strength. Containers placed along paths or around decks create a sense of structure and privacy, while providing displays of life and color.

Before you move on to the following lists of ergonomic tools and plants to consider for your garden, consider Eddison's sage advice for the aging gardener: “Our best hope of a simpler way to garden is to follow nature and learn to go with the flow.”

Ergonomic Tools and Tool Suppliers: Loppers and pruners with soft grips; ratchet loppers and pruners; pole saws with extension handles; lightweight durable ultra-flexible kink-free garden hoses such as those made by Zero-G; digging and weeding tools such as those made by Radius Garden tools; hori hori knives; short- and long-handled weeders; shovels with U-handles; kneeling pads and benches; rolling seats; aprons with deep pockets.

Battery-Operated Tools: Blowers, hedge trimmers, lawn mowers, weed whackers, hand spreaders.

Other Tips: Use lightweight containers or rolling carts for hauling; plant in raised beds; use a pool siphon for cleaning ponds and water features; keep a cell phone or whistle with you when gardening; take frequent breaks to stand and stretch; stay hydrated.

For More Information: www.gardeners.com ; www.patriot-products-inc.com ; www.radiusgarden.com ; www.garden.org/learn/articles

List of Easy-Care Plants for Butte County (compiled by Dana Drennan, UC Master Gardener of Butte County)

Shrubs: Callistemon (bottlebrush); Cercis (redbud); Chaenomeles (flowering quince); Cistus (rock rose); Cotinus (smoke tree or smoke bush); Dodonaea (hop bush); Grevillea; Echium; Lavandula (bush lavender); Osmanthus (sweet olive); Prostanthera (mint bush).

Perennials: Achillea (yarrow); Anigozanthos (Kangaroo Paw); Caryopteris (Bluebeard); Epilobium (California fuchsia); Hemerocallis (day lily); Iris (see below); Origanum (oregano); Nepeta (cat mint); Perovskia (Russian sage); Salvias; Solidago (golden rod); Teucrium (Germander); Westringia (Coast rosemary); grasses such as Bouteloua, Carex, Muhlenbergia, and Stipa.

List of Lower-Maintenance Perennials (compiled by Eddison)

Sedum 'Autumn Joy', Agastache “Blue Fortune”, ornamental grasses, Liriope, Boltonia asteroides “snowbank”, Amsonia, Aster 'Raydon's Favorite', lamb's ears, Siberian iris, and daylilies.

SOURCES:

Sydney Eddison, Gardening for a Lifetime: How to Garden Wiser as You Grow Older (Timber Press, Timber Press).

Susan Harris, 10 Great Things about Gardening for a Lifetime, at www.gardenrant.com

Tags: Butte County Master Gardeners (30), Perennials (1), senior garden tools (1), senior gardening (1)

Focus Area Tags: Yard & Garden

Monarchs and Milkweed

Published on: April 5, 2019

By Kim Schwind, UC Master Gardener of Butte County, April 5, 2019

In recent months there has been disturbing news about the decline of the Western Monarch population. The North American Monarch Butterfly (Danaus plexippus) is a familiar and charismatic insect. It is known for its amazing migration and its reliance on one plant in particular: milkweed.

Monarchs in Michoacan by J. Alosi

The monarch spends the winter along the California and Mexico coastline. When early spring arrives these butterflies begin a long distance, multi-generational migration. They travel as far as Arizona, Nevada, Idaho, Utah, Oregon, and Washington.

There are many hazards along the way. The monarchs that start their migration in the spring will not live long, so in order to lay their eggs they must locate a stand of milkweed. Once laid, it takes three to five days for the eggs to hatch into caterpillars. Monarch caterpillars feed exclusively on milkweed. They grow and molt through five developmental stages over a span of 14 to 18 days. Each caterpillar then spins silk attaching itself to a milkweed leaf or stem and forms a chrysalis (hardened outer protector). After about 10 days it emerges from the chrysalis as an adult butterfly. The lifespan of this adult butterfly is very short – just two to six weeks. In that time it feeds on nectar and continues the migration journey. It might take three or four generations to reach the end of the migration. The last generation (which has a lifespan of months rather than weeks) flies back to its ancestral start where it overwinters in large trees. In Pacific Grove, California they overwinter in a large grove of eucalyptus trees.

Monarchs over wintering in Michoacan by J. Alosi

Monarch in Michoacan by J. Alosi

As of February 2, 2018, according to the Xerces Society for Invertebrate Conservation, monarch populations in western North America were at their lowest point ever. There used to be millions of monarchs that overwintered along the Pacific Coast of California and Mexico. There were an estimated 4.5 million in the 1980s. In 2018 the annual Xerces Western Monarch Thanksgiving Count totaled only 28,429. The population is now 6% of what is was in the 1980s.

The reasons for Monarch decline are varied, and include habitat loss, disease and predation, use of herbicides and pesticides, and climate change.

What can be done to help these beautiful pollinators?

Backyard gardeners can help restore breeding and migratory habitat here in

Showy milkweed by J. Alosi

Butte County by planting native milkweed and nectar-producing flowers that bloom from spring to fall. This can be as simple as planting annuals like zinnias, sunflowers, and asters in your garden. Even if your garden is small you can dedicate a small area or container to pollinator-friendly flowers.

Milkweed is a perennial plant. It is named for its milky, latex sap. Milkweed is drought tolerant and deer resistant. The native species are not invasive. Milkweed plants develop large fleshy seed pods. When the seeds are mature, the pods pop open, freeing the seeds. Attached to the seeds are fine tufts of hairs (called pappus) which aid dispersal of the seeds: as the wind blows, it catches the silky hairs, carrying the seeds away from the plant. The seeds can be collected from the pods for later propagation or left alone to re-seed themselves.

Seed pods and flower tassels on showy milkweed by A. Springerr

Milkweed belongs to the genus Asclepias. The California native milkweed species that are most commonly available commercially and grow well in this area are narrow-leaved milkweed (A. fascicularis) and showy milkweed (A. speciosa). Other native milkweed species that are not commonly available include California milkweed (A. californica), wooly milkweed (A. vestita), woolypod milkweed (A. eriocarpa) and heartleaf milkweed (A. cordifolia), which is suited to the Sierra foothills.

Home gardeners can aid the Monarch population by adding milkweed to their landscape, pollinator garden, herb garden, or even a patio container. If you own a larger plot of land you might consider letting some of it remain wild, so that the wild nectar producing flowers are available not only for butterflies, but for other pollinators as well. Hedgerows that include milkweed and nectar flowers are a wonderful way of attracting wildlife and pollinators. Creating a monarch way station (a garden that includes milkweed, nectar flowers and a water source) is a nice addition to a community or school garden.

Monarch caterpillar by Kim Schwind

Once the monarch lays its eggs and the caterpillars hatch, they will devour most of the leaves on the milkweed plant. By the time the caterpillars are ready to morph into chrysalis, the plant will look dead, but don't despair -- the leaves will grow back.

Milkweed is also a great host plant for many other beneficial insects including bees, beetles, and lady beetles (ladybugs). It will also attract a yellow aphid known as Oleander aphid. This aphid will not destroy the plant and it will not infest nearby roses or vegetable gardens. It is plant specific: think of the Oleander aphid as food for the lady beetles.

Avoid using pesticides or herbicides that might damage these breeding and feeding areas. Use caution where you plant the seeds, as milkweed can be toxic to livestock.

Area specific milkweed seeds can be purchased online. You can also find milkweed plants at our upcoming Master Gardener plant sale on Saturday, April 20^th, from 10 a.m. to 2 p.m. at our Demonstration Garden at Patrick Ranch, located at 10381 Midway, Durham. For more information on the plant sale, see the Butte County Master Gardener website at https://ucanr.edu/sites/bcmg/

For more information on Monarchs and milkweed, visit the Xerces Society for Invertebrate Conservation. Their website also includes area-specific nectar plant lists.

Monarchs en masse in Michoacan by J. Alosi

For information on area-specific native plants, including milkweed, the Theodore Payne Foundation is an excellent source.

Finally, local butterfly experts highly recommend Monarchs and Milkweed: A Migrating Butterfly, a Poisonous Plant, and Their Remarkable Story of Coevolution by Anurag Agrawal (2017).An interview with Agrawal on this subject recently aired locally on the North State Public Radio program Cultivating Place, and is available as a podcast here.

For more information on gardening in our area, visit our website Butte County Master Gardener. If you have a gardening question or problem, call our Hotline at (530) 538-7201 or email us at mgbutte@ucanr.edu.

Milkweed seeds by Laura Lukes

Tags: Butte County Master Gardener (38), milkweed (1), Monarch (1), showy milkweed (1)

Focus Area Tags: Yard & Garden

The Buckeye

Published on: March 22, 2019

Finding an Ecological Niche: A Three-Part Series on Selected Foothill Woodland and Chaparral Species, Part 3 of 3: The Buckeye

By Laura Lukes, UC Master Gardener of Butte County, March 22, 2019

[Note: Buckeye (Aesculus californica), gray pine (Pinus sabiniana), and blue oak (Quercus douglasii) are tree species that thrive in rugged local foothill woodland and chaparral habitat. In the last two editions, we covered the blue oak and the gray pine. This final installment explores the buckeye. All three species rely on adaptive strategies evolved over time allowing them to thrive in their challenging environment.]

Buckeye in Upper Bidwell Park by J. Alosi

Our California buckeye has doubled down on the ecological playing field: it's the high roller of the hardy foothill species explored in this series. Sonoma County Master Gardener Sue Ridgeway describes the California buckeye as “a species superbly adapted for survival,” because not only does it have a growth habit designed to circumvent drought conditions, but also “a highly effective reproductive strategy,” with leaves and shoots protected from grazing animals by noxious, toxic compounds; prolific flowers attracting multiple native pollinators; and viable seeds too poisonous to be consumed. On a biological scale, the gamble has paid off: buckeyes have an estimated lifespan of 250 to 300 years.

Aesculus californica is a woody shrub or small tree that has adapted to a variety of microclimates in our state: it can be found along the central coast and in the foothill and lower montane elevations of the Sierra Nevada and Cascade Ranges. It grows as far north as the foothills of the Siskiyou Mountains, and as far south as northern Los Angeles County. Native buckeyes can grow in elevations as high as 4,000 feet (one source claims 5,500 feet), but most commonly these plants colonize the foothill altitudes. A true California native, it is found nowhere else in the world.

Buckeye leafs out early in the spring by Eugene Zelenko

Buckeyes are a beautiful and striking presence on the landscape. In fact, this native is so lovely that it is used as an ornamental plant for its attractive lime green palmately compound leaves[JHC1] (shaped like the palm of the hand) composed of between 5 and 7 individual leaflets, fragrant white flowers, and handsome, thick-stemmed, smooth silver bark. Its stands out visually from its fellow foothill species precisely because of its evolutionary adaptations: it is the first to leaf out in the spring; the last to bloom; and the first to lose all its leaves. In particularly hot, dry years, the leaves can drop prior to the blooms, making the large, showy flowers (up to 12 inches long) even more conspicuous. When leafless, the skeletal structure of mature buckeyes appears to be sculpted and arranged by the hand of an artist.

The California buckeye's variable height attests to its nuanced response to climatic conditions: in northern reaches, the buckeye is shrubby and squat (about 12 feet tall). Further south, it can reach tree-like statures of up to 30 feet. In the kinder habitat conditions of the Coast Range, an Aesculus californica has attained sufficient proportions to be registered as a California Big Tree. That one, in Swanton Pacific Ranch, measures 46 feet high, has a trunk circumference of 176 inches, and a crown that spreads to 60 feet.

The seeds of Aesculus californica are contained in a thick leathery husk, which splits when dried, and are the largest of any non-tropical plant species. These seeds (also called nuts) are the origin of both of its common names: buckeye and horse chestnut. According to Cal Poly's Select Tree web page, Native Americans called the seed "hetuck" (buck eye) because its markings resemble the eye of a deer. The seeds also resemble those of the European sweet chestnut (Castanea sativa). And there the resemblance ends, as the heavy seeds of the California buckeye are toxic, thus limiting its reproductive dispersal strategies to rolling downhill or being conveyed by water.

In addition to toxic seeds, the buckeye's leaves, shoots, and flowers are poisonous. All contain the neurotoxin glycoside aesculin, which is destructive to red blood cells. Although ruminants can feed on very young shoots without harm, and squirrels are able to tolerate the nuts, this toxin protects the buckeye from damage or death by grazing animals. As Ridgeway points out, “the sweetly fragrant flowers of this tree provide a rich pollen and nectar source for native bees, hummingbirds, and many species of butterflies” and are toxic only to non-native honey bees. Honey bees that do survive after ingesting buckeye toxins reproduce “buckeyed-bees” that hatch with deformed, crippled wings or malformed legs and bodies.

Buckeye's namesake is the large nut by John Moran

Surviving Drought and Fire: Buckeyes employ two of the most successful adaptations to Mediterranean climates: drought avoidance and a long taproot. These trees begin their annual growth cycle in the late winter and early spring rainy season, and enter dormancy in summer. By shedding their leaves early, they avoid loss of water from transpiration through the leaves. This adaptation to our long, hot, dry summers gives the plant a nice long rest period before the rains begin.

A deep taproot allows the buckeye to find water in even the driest of years. A fully developed root system also helps mature California buckeyes to survive drought by enabling the plant to both save and draw on food and water reserves. According to USDA research, California buckeyes recover rapidly following a fire, sending out new shoots during the first growing season, and growing rapidly in following seasons. Some buckeyes can exceed their pre-fire biomass within a few years. They can sprout from their root crown after top-kill by fire within a few weeks, even in the summer months. The USDA also notes that buckeye seeds will probably not survive fire because they are highly susceptible to desiccation by heat.

Buckeye flower spike by Eugene Zelenko

Native American Uses: Native groups did find the buckeye nut to be of some use as a food supply despite its toxicity, primarily when acorn harvests were sparse. They rendered the buckeye seed palatable by boiling and leaching the toxin out of the nut meats for several days, after which the nuts could be ground into meal similar to that made from acorns.

The same toxin that limited the buckeye seed to a food source only in times of hunger was used to snare a more delicious high protein food source. Native California tribes, including the Pomo, Yokut, and Luiseño, cleverly used the ground-up powder of buckeye seeds to stupefy schools of fish in small streams, making them easier to catch. And the smooth, straight branches of the buckeye made it useful to native peoples as a bow drill and a fire drill.

Our native buckeye is a California beauty and a hardy survivor in some of the least hospitable habitats. In the biological contest for survival, this tough, gorgeous plant holds a winning hand.

For more information on gardening in our area, visit the Butte County Master Gardener web page at: http://ucanr.edu/sites/bcmg/. If you have a gardening question or problem, call our Hotline at (530) 538-720l.

Sources:
Sue Ridgeway, The Bisexual California Buckeye – sinner or survivalist? UCANR website: http://sonomamg.ucanr.edu/Plant_of_the_Month/Aesculus_californica_-_California_buckeye/

M. Kat Anderson, Tending the Wild: Native American Knowledge and the Management of California's Natural Resources (University of California Press, 2005).

Urban Forests Ecosystem Institute at CalPoly SelecTree: https://selectree.calpoly.edu/tree-detail/Aesculus-californica

Yosemite Hikes: https://www.yosemitehikes.com/wildflowers/california-buckeye/california-buckeye.htm

Stanford Trees: https://trees.stanford.edu/ENCYC/AEScal.htm

USDA: FEIS: FIRE EFFECTS INFORMATION SYSTEM: https://www.fs.fed.us/database/feis/plants/tree/aescal/all.html#FIRE%20ECOLOGY

Carol Bornstein, David Fross, and Bart O'Brien, California Native Plants for the Garden (Cachuma Press, 2005)

https://fog.ccsf.edu/~btraut/documents/Aesculuscalifornica.pdf

Wikipedia: https://en.wikipedia.org/wiki/Aesculus_californica

Photo Credits:
Buckeye's namesake is its large nut: By John Morgan from Walnut Creek, CA, USA - IMG_8269, CC BY 2.0, https://commons.wikimedia.org/w/index.php?curid=25021982

Buckeye flower spike: By Eugene Zelenko - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=2103608

Buckeye leafs out early in the spring: By Eugene Zelenko - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=18732498

Tags: Aesculus californica (1), Buckeye (1), Butte County Master Gardener (38), Chaparral Species (1), Foothill Woodland (2)

Focus Area Tags: Yard & Garden

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