A CALIFORNIA ESSENTIAL
EVERY year, as summer shortens into autumn, cricket song swells in a yard up the street. The tree crickets will chorus from nightfall to dawn, every night through October, until they have seduced a female or died trying. No other music manages to be so elegiac and at the same time so hopeful. Or, on my street, so mysterious. The yard where the crickets sing is concealed by an immense house. According to the old timer who lives next door, Wally Matsuura, the song comes from an oak.
The sound is so beautiful that for years now, I have tried to lure the crickets into my garden. Nothing was too good for them. I planted Italian olives, Carolina cherries, French lavender, Japanese box hedges and Spanish citrus. No crickets.
French grapes, Mexican passion vines, China roses.
Still no crickets.
Australian acacia. South African bird of paradise. Canary Island sage.
Not even for Moroccan oleander or Chinese bamboo would they leave their oak.
It turns out that the oleander is deadly to them, and a Southern California tree cricket has as much use for bamboo as a Chinese panda bear has for a Joshua tree. Tree crickets from California need trees from California -- the same roots, trunk, bark, leaves and stem that they evolved with over millenniums. In the case of the crickets, and so much of Californian fauna, the source of life is the state’s native oaks.
A fine Cachuma Press book, “Oaks of California,” outlines how the trees support a huge swath of our flora and fauna, from lichens and mistletoe to gall wasps, squirrels, boar, deer, hawks, eagles, condors, even, once upon a time, grizzly bears. The California Oak Foundation tops the Cachuma roll call with a list that includes salamanders, toads, lizards, warblers, turtles -- on and on for hundreds of creatures, ending with yellow pine chipmunk and Yuma myotis, whatever that is. According to the book, oaks are such rich “islands of life” that the Spanish missionaries followed the coast live oak ranges north when they first penetrated California.
Not every native oak attracts every critter. Twenty species, 11 shrub oaks and nine vaulting tree forms, each develop distinct ecosystems. I wanted the one that attracted crickets, to be precise snowy tree crickets, or Oecanthus fultoni. The trick was finding out what it was.
We already had a fine coast live oak growing between our houses, Wally and me. It clearly wasn’t a cricket oak. According to Wally, it just appeared one day and he never got around to cutting it down. By the time he had to decide its fate, it had already attained a poetic leaning form all too rarely seen outside of wild oaks, because the nurseries selling box oaks for gardens tend to stake them to stand up ramrod straight, then prune them to have perfect bulb-shaped canopies. He says he spared it because someone told him that it increases the value of his house.
I think he fell in love.
An oak can steal your heart. You won’t read this in plant books, but oak trees are stealthy. If someone tells you that oaks are slow growing, they are repeating a widely accepted myth and haven’t lived with a young oak. Inspired by Wally’s oak, I put two coast live oaks, nursery plants from 24-inch boxes, in my front yard. At first they were pitiful, and made small dogs seem big, but only seven years later, they are reaching the second story.
New oaks are even faster from acorns. A 20-year-old-seedling, Wally’s coast live oak is easily 40 feet high. Its boughs sweep out after the setting sun like a dancer in some Merce Cunningham interpretive deal, except in a tree it’s not pretentious. Squirrels run riot in it. Three sorts of woodpeckers work the bark, drilling for sap and grubbing insects or maybe just sharpening their beaks. The tree also fills up with bushtits each year, funny chattering birds that glean it of wasps and other meaty bugs before descending from its canopy into my garden and systematically stripping all the plants below of pests.
Coast live oaks are evergreen, which doesn’t mean that they don’t drop leaves, but that they don’t do it all at once. In fact, they shed enough to be self-mulching and even allow some to be carried off to improve vegetable beds.
On the tree, these oval leaves are tough and stout, with slightly serrated edges. They come in a dusky shade, a color that seems mixed from silver, blue and a deep coniferous green and is so right for cutting Southern Californian glare.
Unlike many California natives, they do not go completely dormant. During the summer, as the water table lowers in the ground, the leaves furl and tighten, but the acorns still slowly plump out. But still these giants cool all beneath them. The whispering breeze traveling through Wally’s oak -- not a droning machine -- air conditions my house.
Every year, I am always surprised how early the acorns ripen here in the southern, hot end of California. Yet the possessive screeches from the trees, followed by quick flashes of electric blue wings, remind me that the acorns are ripe now. Blue jays follow the acorns and know their ripening time so well that out in La Canada Flintridge, native plant curator Kevin O’Connell tells me that jays have already stripped the fruit from dozens of acres of oaks in Descanso Gardens.
The Cachuma book estimates that a single blue jay will cache thousands of acorns every year. The nuts, with their perfect mix of fat, carbohydrates and protein, should last the birds a year. Another way to look at California’s heroic oak ranges is as the forgotten dinners of blue jays.
Unfortunately, we cut oaks down faster than the jays and nature can replenish them. The problem isn’t simply that California’s vast stretches of wild oaks have been cleared to make way for farms, then suburbs, but that when we move in, we replace these native “islands of life” with crops and ornamental plants that have little or no wildlife value.
People like me try to lure crickets with all the wrong plants. Or we are fooled when developers insist that they can safely move the trees. Here, Ventura County, you still have a thousand oaks but in all different places. This almost invariably kills them, says Ted Swiecki, a plant pathologist who runs Phytosphere Research in Vacaville, Calif.
“They can look all right for a few years,” he says, “but a huge fraction of them, if not all of them, will end up dying.”
Anyone interested in the conservation issues surrounding oak preservation should head straight to the website of the California Oak Foundation, www.californiaoaks.org. For homeowners, the safest way to have an oak in your yard, to do your bit to keep California Californian, is to build respectfully around an existing tree -- or plant a new one. Somehow this calls for an occasion. Oaks can live hundreds of years. Trees that will outlive the next five generations are a different order of commitment than an apple tree that may make it two decades. This is particularly true where preservation orders apply.
When my father died, I decided that I would finally put in a cricket oak. He always loved the sounds that rose out of gathering dusk. Last autumn, I bought an Engelmann oak, a similar-looking tree to the coast live oak, but with tapered almost-blue leaves and saucy fat little acorns. It is native to our region and an alternate name is “Pasadena oak,” but developers have left nary a trace of them. I planted it near the live oaks, just before the winter rains. The ashes, they would only go in once I heard the first cricket sing from its boughs.
But as the crickets began singing this autumn, they hadn’t come to the Engelmann, any more than the live oaks. I called cricket experts and oak experts. None knew which oak made a garden a concert hall.
One scientific paper suggested that it was an Oregon oak. Evidently, tree crickets are partial to them in the Pacific Northwest. But the California native tree experts laughed. Each night the crickets sang. It came down to talking my way into the garden with the cricket oak down the street. This belongs to a retired dentist named Louise Watson. There in Dr. Watson’s backyard stood a tree that was completely different.
The cricket oak was immense. It must have gone in when the house was built in 1904 or been there when it went in. Some cruel cuts had accommodated power lines. The tree had flat leaves, more like an English oak, and it was already molting -- it was clearly deciduous. Revealed through the thinning canopy were three large nests.
As Dr. Watson herself appeared in the yard, she looked up at the nests and remarked that some years ago, she’d seen an owl in the tree after her husband died.
After sending leaf samples to Dave Fross, founder of Native Sons nursery in Arroyo Grande for a second opinion, he came back 90% sure that the cricket tree is a valley oak. That is, says Fross, the most majestic of California oaks and a type once common the length of the Central, Santa Clarita and San Fernando valleys, though it is now disappearing. According to Tom Scott, a hardwood specialist at UC Riverside, Dr. Watson’s oak was at the southern end of their distribution.
There is also a likely scientific explanation for why the crickets insist on her valley oak instead of my coast live oaks. They might be too specialized. Unlike the coast live oaks, which belong to an evolutionary line called red oaks, the valley oak belongs to a different line, or sub-genus, called white oaks. Engelmanns are also white oaks, I learned, so I might be in luck as the sapling grows.
There are only so many big trees that a gardener can plant to satisfy an operatic bug. There is no way any of the coast oaks are coming out. It would be a crime against mourning cloak butterflies, bushtits, squirrels and jays. The Engelmann is staying, too, right now only for its dusky shade of Pacific blue.
Standing in Dr. Watson’s backyard, staring up at her century-old tree, at the edge of its natural range, the source of the only wild night music for miles around, I realized I was about to add a third species of oak to a lot that is a fifth of an acre. I would have to tear out some of the citrus and passion vines. In their place, I would put a valley oak, another island of life.
Emily Green can be reached at firstname.lastname@example.org.
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Planting season for natives is late October and November, in advance of winter rain, so now is the time to start asking yourself: Which oak and why?
Of 20 species of oaks native to the state, five trees are suitable for Southern California. These divide into three sub-genera -- red oaks, white oaks and intermediate oaks -- all of which have distinct leaves, acorns, wood and very possibly host-plant relationships with wildlife.
Coast live oak (Quercus agrifolia). Red oak or sub-genus Erythrobalanus. Most suitable native for much of Los Angeles and the coastal region, from Mexico three-quarters of the way to Oregon. Its oval, evergreen leaves will constrict with drought and plump with water, and its range provides vital shelter to native jays and migrating song birds, including tits and warblers. Evergreen leaves allow it to produce nutrients and grow faster, though adding water and pushing growth may shorten life span. Grows fastest from acorn, but taken from a nursery box, will become 20 feet in eight years, 40 feet in 20 years. Slows as matures. If lifespan exceeds 250 years, crowns can be 80 to 120 feet across.
Interior live oak (Quercus wislizenii). Red oak or sub-genus Erythrobalanus. Broad-based, broad-canopied evergreen inland answer to coast live oak. Important for mixed oak forests, but running in a distinct band east of coast live oaks along the Sierra. Tough leaves more resistant than some to browsing by deer.
Valley oak (Quercus lobata). White oak or sub-genus Lepidobalanus. Have regal metaphors ready to discuss this oak, alternately described as lordly, the monarch of California oaks, noble and majestic. So distinct from coast live oaks that while the Spanish call a coast live oak encino, the word for valley oak is roble. In form, the valley oaks are the most like European oaks, with an upright, balanced habit and deeply etched bark. Leaves are flat, lobed and slightly fuzzy. Acorns can be round or more tapered cylinders. When California was settled, the great inland valleys were covered with Quercus lobata. Today, the trees are rare in Southern California and endangered in the Central Valley, where shrinking water tables are hurting the ones that escaped clearing by farmers and developers. Drought can make them look ratty. Capable of living hundreds of years, attaining massive girth and towering hundreds of feet.
Engelmann oak (Quercus engelmannii). White oak or sub-genus Lepidobalanus. Also known as the Pasadena oak. The best adapted oak to the region is the rarest. The Southern Californian oak native to Riverside, San Diego and Los Angeles counties once made up woodlands between San Diego and the Arizona border. So annihilated by development that the foresters and botanists who wrote “Oaks of California” describe it as the most imperiled of all tree oaks in the state. Left in a wild state, more likely to spread out rather than up, with deep blue-green leaves that may fall in cases of drought but recover with rain. Medium-size, from 20 to 30 feet tall, life span of 150 years or longer.
Canyon oak (Quercus chrysolepis). Intermediate oak or sub-genus Protobalanus. Grows the length of California in foothills and canyons, its form surrounded by neighboring landscape. Evergreen, capable of living 350 years, developing a 10-foot trunk span and clinging low to the ground unless competition for light forces it upward. From 20 to 50 feet tall, as wide or wider.
-- Emily Green
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Pamela C. Muick, coauthor of “Oaks of California,” likens the choice of an oak for a garden to choosing a fine antique. The oak’s going to become one. The most important thing will be selecting the right tree and learning the right way to care for it so that nature works for and not against you.
Choosing a spot: “Make sure you have plenty of room,” says Muick. These trees can develop canopies that are 80 to 150 feet across. Some will develop trunks that are 10 feet wide. Because oaks are wind-pollinated, preservationists implore those living near wild oak communities to stick with the dominant species, coast live oaks in coast ranges and so on, so as not to introduce foreign pollen and weaken the long-adapted genetics that equip the trees to survive.
Planting an acorn: Dave Fross of Native Sons nursery, Muick and Ted Swiecki, plant pathologist of Phytosphere Research in Vacaville, agree: Think big and start small. The best tree will come from an acorn, whose tap root will be a meter deep before a sprout even appears. The most serendipitous planting, says Fross, is done by jays and squirrels. The gardener’s art is letting the well-placed ones live. “They cache them inside shrubs. The shrub acts as a nurse. Coast live oaks are shade tolerant as young trees,” he says. “Just let them go. Rip the hedge out and let the tree come.”
Moving oaks: Don’t, not even seedlings. Damage done to the tap root is why digging out even the tiniest seedlings rarely works and moving mature oaks invariably kills the trees.
Planting an oak sapling: In nurseries, root systems become circularized as they adapt to the pots. Look for a tree that is not pot-bound, and if roots are growing in circles, gently untangle them. If seriously root-bound, return the tree. After the tree is planted, water the hole, allow it to absorb, water the planted tree, then allow it a month to adjust and drain before watering again.
Root systems: With trees planted as acorns or nursery saplings, when they mature, their root systems will spread to twice the width of the canopy and concentrate from 6 inches to 3 feet beneath the surface of the soil. When digging trenches for utilities or putting in swimming pools and garden structures, visualize the roots before digging and be aware that damaged root systems are the most common entry points for fungal disease. When oak trees fall over, they are usually in lawns and it is a safe bet that their roots have been rotted by sprinkler systems.
Watering: Fungi that are present in most soil and benign in normal circumstances can become lethal with irrigation. Except for monthly, slow waterings on a trickle line for several hours during the first several years after an oak is planted, it should not be watered. The fetid conditions encourage disease. If a plant appears stressed by drought, Muick encourages slow watering in early summer or end of summer, but not midsummer, when the plant will be slowing its metabolism to cope with reduced water. Espaliering oaks, as the garden designers of the Cathedral of Our Lady of the Angels in downtown L.A. did, is gardening masochism and involves a long tour in purgatory, or possibly a drop straight to hell.
Companion planting: Beware material from conventional nurseries because of the boggy nature of potting soil and the potential of pathogen growth from routine over-watering. Surround young oaks with native and Mediterranean plants that can accept the same water regime: lavender, manzanita, ceanothus, artemisia. As the trees mature and shade slowly retires the sun-lovers, remove these and replace them with woodland natives such as coral bells. The beauty of oaks, with mulch, rock and picnic tables, should not be underestimated.
For more advice on companion planting, the booklet “Compatible Plants Under and Around Oaks” is available through the California Oak Foundation, 1212 Broadway, Suite 842, Oakland, CA 94612; (510) 763-0282; www.californiaoaks.org.
Pruning: Avoid pruning saplings. Trees that look from seedlings like they will four-way crowns will correct their own habits as they grow. The best time to prune an oak is during dry season, when rain and night fog will not increase the chance of fungal diseases taking hold. From now through October is ideal. Make sure you use a licensed arborist.
Mulch: Leave oak litter to protect soil from evaporation and erosion. Contrary to common practice by city arborists, never run asphalt or concrete under the crown of an oak.
Oak root fungus and sudden oak death: The 2002 fifth edition of “Oaks of California” addresses both diseases. For more information on prevention, consult the California Oak Foundation, go to Phytosphere at www.phytosphere.com/onlinelist.htm or contact your nearest UC Extension horticulturist.
Recommended reading: “Oaks of California” by Muick, Bruce M. Pavlik, Sharon G. Johnson and Marjorie Popper (Cachuma Press, $22.95).
-- Emily Green