From the north end of the Sacramento Valley to the San Fernando Valley, the valley oak, Quercus lobata, is among the most familiar and distinctive of native oaks. It is the largest oak of North America, reaching more than a hundred feet tall with trunks as wide as ten feet, which is why it is rare in urban gardens. The hundred fifty foot tall ‘Henley Oak’ of Covelo is the tallest hardwood tree in North America. The oldest trees are about six centuries old.
The two or three inch long leaves have deep and round lobes. The foliage turns only dingy yellow and then brown in autumn, and can be messy as it continues to fall through early winter, particularly since the trees have such big canopies. The gnarly limbs are strikingly sculptural while bare through the rest of winter. The gray bark is evenly furrowed.
Incidentally, Oakland, Thousand Oaks, Paso Robles and various other communities within their range are named for valley oaks. (‘Roble’ is the Spanish name.)
From the northern end of the Sacramento Valley to Santa Catalina Island, valley oak, Quercus lobata, is as Californian as Valley Girl. It inhabits mixed riparian forests and low hillsides up to about 2,000 feet, but prefers alluvial valley meadows in between. Although unpopular for landscaping, it sometimes self sows into home gardens. New landscapes sometimes develop around old trees.
Valley oak is one of the biggest of oaks, and the tallest oak of North America. Mature trees can be more than a hundred feet tall, and several centuries old. Trunks may be more than ten feet wide. Such big trees make big messes of acorns and deciduous foliage, which shed for weeks. Unfortunately, old valley oaks within new landscapes are susceptible to spontaneous limb failure and rot.
Where space is sufficient, new valley oaks are for future generations. They develop their distinctively sculptural branch structure slowly through several decades. If irrigation is not excessive, roots are remarkably complaisant. The evenly furrowed gray bark is rustically distinguished. The elegantly lobed leaves are about three inches long and half as wide. Yellowish autumn color is subdued.
The biggest valley oak in the Santa Clara Valley supposedly lives next door to where I lived in town. Well, that was too far to go to get the picture I needed for the garden column next week. Another lives on the other side of the tracks.
1. Roaring Camp Railroad is out back. The Depot is out of view to the right, on the other side of Zayante Creek. The big valley oak that I got a picture of is on the left, but does not look so big from here. A few ecosystems mix here, so ponderosa pines, Douglas firs and all the riparian trees mingle with the coast live oaks and redwoods. However, I doubt that valley oaks are native.
2. Rhody stayed home. These grates on the pedestrian catwalk on the bridge are not intended for small paws. Some of those trees down there are about thirty feet tall! Most are white alder.
3. Riparian trees are close enough for pictures from a pedestrian bridge just downstream. That foliage in the middle of this picture is a sycamore. However, the deteriorating bridge is closed.
4. Old valley oaks, which are native just a few miles away, seem to have been planted here; since they all are on roadsides or driveways. Whether native or introduced, they happily self sow.
5. Moss makes these sculptural limbs seem to be older than they are. This now massive valley oak was a shrubby young pup in photographs from the 1920s. It was likely planted after 1906.
6. Gnarly roots were exposed by erosion on an embankment between the big valley oak and the train tracks. I suspect that the tree was planted to shade the depot during the late afternoon.
This is the link for Six on Saturday, for anyone else who would like to participate:
Before the 49ers of the Gold Rush discovered that the seeds of the native coffeeberry, Rhamnus californica (or Frangula californica), make a nice uncaffeinated coffee substitute, the native American Indians were eating the fruit and using the leaves and bark herbally. The black berries supposedly make good jelly, but do not last long, and are too bitter while still red or greenish.
Before the birds get them, the quarter inch wide berries are somewhat colorful, but are not very abundant. The small clusters of tiny greenish yellow flower that bloom in spring are not much to look at either. The army green evergreen foliage is the main appeal. New stems are somewhat ruddy. Old stems and main trunks have smooth gray bark.
Large coffeeberry plants in the wild can get more than ten feet tall, with relatively open branch structure. Garden varieties stay smaller, with compact branch structure. ‘Eve Case’, which is probably the most popular variety, stays less than six feet tall, and is densely foliated. ‘Mound San Bruno’ is even more compact, with smaller leaves. ‘Seaview’ is a groundcover.
Its natural coastal range extends from the extreme southern corner of Alaska to the southwestern corner of California. Another inland range occupies foothills of the Sierra Nevada. Bigleaf maple, Acer macrophyllum, is the most common and prominent native maple here. However, it prefers the seclusion of forested riparian situations at higher elevations locally. It is rare in urban gardens.
Bigleaf maple is best in the wild anyway. It dislikes the aridity of most of the urban and suburban areas of California. (San Jose is in a chaparral climate. Los Angeles is in a desert climate.) Roots of bigleaf maple are potentially aggressive, especially if irrigated generously. They easily displace pavement. Nonetheless, where climate and circumstances allow, bigleaf maple is a grand tree.
Wild trees grow as tall as a hundred fifty feet within forests where they compete for sunlight. Well exposed suburban trees should stay lower than forty feet, while extending their canopies broader than tall. The big and palmately lobed leaves are mostly more than six inches wide. Foliage turns yellow in autumn, and is abundant as it falls. Self sown seedlings often grow under mature trees.
California native plants are logical options for the gardens and landscapes of California. It is only natural. They are already happy with the climates and soils here. They do not need to adapt quite as much as plants from other regions and climates do. After all, they lived here long before anyone else was here to water and maintain them.
Unfortunately, it is not that easy. California is a very diverse place. There are more climates here than there are within many other states combined, over a much larger area. Plants that are native to the Mojave Desert would not be happy in a rainforest of the Siskiyou Mountains. Coastal plants would be no happier high in the Sierra Nevada.
Within reason, California native plants for landscapes and home gardens should be either locally native, or native to similar climates. Plants from very different climates within California are about as exotic as plants from other continents. Just like foreign exotic plants, they may require special accommodation, such as irrigation, to survive here.
All plants need irrigation when first installed. Irrigation can be slightly complicated for plants that are native to climates with long and dry summers. They certainly need irrigation until they disperse their roots. However, a bit too much can rot their roots. California native plants can be sensitive like that. After all, they do not expect to be moist through summer.
Then, once established, many California native plants do not want frequent irrigation. Many want none at all. Chaparral plants like oak, manzanita, toyon, ceanothus and coyote brush tend to rot with too much watering. Plants that are native to riparian or coastal regions, like redwood, bigleaf maple, willow, cottonwood, elderberry and ferns, tolerate more irrigation.
Most California native plants that are from chaparral or desert climates do not perform well within the confinement of pots or planters. They prefer to disperse roots very extensively and directly into the soil, just like they do in the wild. Once established, they do not transplant easily.
Ohio is the Buckeye State. The Ohio buckeye that is native there must be very special. Perhaps all other trees that are native to Ohio are just not very uninteresting. Whatever the situation, I sort of believe that the Ohio buckeye is more appealing in some regards than the California buckeye that is native here. However, the California buckeye might be more weirdly interesting.
The main reason that California buckeye is not popularly used in landscapes is that it is ‘twice deciduous’. That means exactly what it sounds like. Just like other deciduous trees, it defoliates in response to cooling autumn weather, and refoliates in response to warming spring weather. Unlike other deciduous trees, it repeats the process through the warmest weather of summer.
When summer weather gets too warm and arid, the foliage of California buckeye shrivels and sort of defoliates. Without rain to dislodge the shedding foliage, it can linger and look shabby for quite a while and maybe until it is replaced by secondary foliage that develops as the weather mellows. The secondary foliage does not last long before it is time to defoliate again for autumn!
California buckeye is not often planted into landscapes because it really does look like the living dead through summer. It provides no shade when shade is most desirable. Those that I work with are only here in the landscapes because they grew from self sown seed that sneaked in on its own. Some will be subordinated to more desirable adjacent trees, although there is no rush.
I happen to like California buckeye. Except for the rarely seen red horsechestnut, it is the only species of buckeye that I am familiar with. Bloom is neither colorful nor reliably profuse, but is delightfully fragrant in close proximity. Not many natives are fragrant.
What a silly name this is! Sticky monkey flower, Diplacus aurantiacus (or Mimulus aurantiacus), is native to a broad range of ecosystems of California and the Northern Coast of Baja California. It is famously happy in situations that are too rocky or sandy for most other species. The resinous foliage really can be rather sticky during warm weather. The relevance to a monkey is a mystery.
Sticky monkey flower is more popular among hummingbirds and insects than anyone else. Those who welcome hummingbirds and insects into their garden happen to like it too. Honestly though, it might a bit too casual for refined landscapes. It works better in or on the outskirts of rustic gardens. If not already growing wild, cultivars and the straight species are available in some nurseries.
Bloom begins late in winter or early in spring, and might continue through summer, but is rarely impressively prolific. The bisymmetrical and tubular flowers are about three quarters of an inch long. Almost all are pastel orange, sort of like circus peanuts. Gold and yellow are uncommon. Supposedly, there are rare cultivars that bloom in red or white. Mature plants get more than three feet tall.
Various species of iris that are native to exposed coastal hillsides are uncommon in nurseries. Even nurseries that specialize in native species grow only a few. Iris douglasiana was probably the most popular of these years ago. Its slender flowers are various shades of steely blue, like faded denim. Nowadays, most Pacific Coast iris are hybrids of various native and a few exotic species.
The color range of these modern hybrids is impressive. Many bloom with rich shades of blue, purple, burgundy, rusty red, orange, gold, yellow or rosy pink. Softer and pastel shades include coral pink, lavender, creamy white and bright white. There is even sky blue that is almost comparable to the color of well faded denim. Flowers are more substantial than those of their ancestors though.
Bloom is sometimes significantly early, or as late as May. Otherwise, it should happen about now. Each floral stalk supports about two or three flowers that bloom in succession. Floral stalks tend to lean outward from the center of mature plants, and curve to hold their bloom upright. Bloom typically stands less than two feet high. Their slender and arching dark green leaves stay even lower.
Most other specie of ceanothus are more colorful and tame than Ceanothus cuneatus is. It is known as ‘buckbrush’ because the abundant round trusses of minute flowers are typically dingy white instead of the more familiar shades of blue that have earned other ceanothus the common name of ‘California lilac’. However, a few wild plants and some garden varieties bloom blue.
Mature plants are at least six feet high and wide, but typically less than ten feet high and twelve feet wide. They are pleasantly fragrant as they bloom between March and April or May. Roots seem to tolerate almost any soil that drains well and does not get watered too much. Once established, no watering is needed. The scrubby evergreen foliage likes full sun exposure.
Although it is a bit unrefined, and does not want to be pruned for confinement, buckbrush works nicely as screening shrubbery on the perimeter of a landscaped area, or in unlandscaped areas. Newly installed small plants only need to be watered occasionally as they disperse their roots through their first year. Since they are native, established plants are satisfied with rainfall.