Japanese Black Pine

Japanese pine is more proportionate to confined urban home gardens than more common species.

Not many large specimens of Japanese black pine, Pinus thunbergiana, can be seen around the Santa Clara Valley. They can get taller than a hundred feet on straight trunks in their natural range on the coast of Japan, but locally, rarely get more than a quarter as tall on leaning and irregular trunks. They just are not quite as happy in the dry air here (minimal humidity). They are purported to be more tolerant of smog than most other pines that were so sensitive to the nasty smog of the 1970’s, but are more likely to become infested with insect pathogens as they get old.

With their angular and somewhat open growth, and classic pine foliage and cones, Japanese black pines are one of the more distinctive pines. Since they do not get too large, they can work well as sculptural specimen trees in small garden spaces and atriums. Even if they grow up above the eaves, their leaning trunks and outstretched lower limbs with rough gray bark are as distinguished as those of larger trees.

The paired somewhat stiff needles are about three or four inches long. The small but stout cones stay green through most of their first year of development, and then turn brown as they mature and open to disperse their seed in the second year. They are only about two inches long, but can become annoyingly abundant among aging trees.

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Atlas Cedar

Amy Carter had the most boss treehouse in an Atlas cedar.

My generation can remember when Amy Carter, the daughter of former President Carter, got a treehouse built in a mature Atlas cedar, Cedrus atlantica, at the White House. It was so cool that it was ‘boss’! Besides being more luxurious than a typical treehouse, it was designed by President Carter to not damage the tree even slightly.

Here in the west, most Atlas cedars are cultivars (cultivated varieties) with blue foliage that often rivals that of Colorado blue spruce. Most have strictly horizontal or angular limbs with stiff, densely foliated branches. Some are so pendulous (weeping) that they need to be staked to be kept off the ground. They actually look great trained along the tops of retaining walls, even without staking, with their blue foliage cascading over. Others are strictly upright and narrow. Colorado blue spruce may have better color; but Atlas cedar has more interesting variation of form.

It is also better adapted to the local Mediterranean climate than spruces and other conifers are, and gets much larger. Mature Atlas cedars can get as tall as a hundred feet, with trunks as wide as five feet.

Grecian Bay

Grecian bay does not get as massive as the native bay laurel.

The native bay laurel should not be confused with the Grecian or sweet bay. Despite the similarities, the native bay laurel grows into a large tree. The foliage can be used as seasoning like Grecian bay, but has a very different and much more pungent flavor. It can often be found fresh in markets, labeled as Grecian or sweet bay, and has likely ruined all sorts of recipes.

Grecian or sweet bay,  Laurus nobilis, stays much smaller much longer. It takes many years to grow to thirty feet tall, often with many trunks flaring out from the center. Trees that are nearly twice as tall are ancient. Because of slow growth, Grecian bay can be happy in large containers as long as it is pruned to stay proportionate to the confined root system.

The three or four inch long, and inch or so wide leaves of Grecian bay can be difficult to distinguish from those of bay laurel. The minor differences are that Grecian bay leaves have slightly undulate margins with a few small and sometimes barely perceptible serrations (teeth) that bay laurel lacks. The leaf apexes of Grecian bay leaves are typically a bit more blunt. For culinary purposes, it is important to be aware that dried leaves and fresh leaves have very different flavors.

Colorado Blue Spruce

With such densely foliated low limbs reaching the ground, Colorado blue spruce functions as much as large shrubbery as a small tree.

Colorado and Utah share the same stately state tree; the Colorado blue spruce, Picea pungens, which is native to the Rocky Mountains between Arizona, New Mexico and southern Idaho. Colorado blue spruce are stoutly conical trees that grow slowly to eventually get more than seventy five feet tall. Where they need to compete with other trees in forests, the biggest are nearly twice as tall with trunks nearly five feet wide. However, because they grow so slowly, and do not get much bigger then they need to, well exposed trees stay proportionate to home gardens for many decades. Many shrubby compact cultivars actually stay less than ten feet tall. Foliage can be grayish green to silvery pale blue. The stiff and sharply pointed needles are about three quarters to an inch and a quarter long, and densely set on relatively rigid stems.

The elegant silvery blue foliage of the Colorado blue spruce is striking either in front of or behind darker evergreen foliage, like that of redwoods or junipers. These stout and densely foliated trees make any garden look a bit more woodsy.

Cork Oak

The bark actually looks like cork.

This is a tree that takes some time to impress. Bloom is uninteresting. Foliage is no more distinctive than that of coast live oak. Instead, the most spectacular characteristic of cork oak, Quercus suber, is the boldly striated and uniquely spongy texture of its mature bark. Such bark takes a few years to develop, but gets so thick that it seems significantly older.

As its name implies, cork oak had historically been the exclusive source of bark for corks and cork products. As modern and more practical materials diminished demand for such bark, cork oak became more popular as an evergreen shade tree. It is quite happy within the arid chaparral climates of California. In fact, it behaves much like native oak species.

Mature cork oak trees generally stay less than forty feet tall, even if their trunks are wider than three feet with their unusually thick bark. Without excessive irrigation, their roots are notably complaisant. Low branches are more visibly sculptural than high branches. With pruning for adequate clearance though, trees with high branches are striking street trees. Foliar and floral debris is quite messy during spring bloom.

Tanoak

Tanoak is rare within refined landscapes.

Its plump and inch-long acorns are misleading. Tanoak, Notholithocarpus densiflorus, is not actually an oak. Otherwise, it would be a species of Quercus. Regardless, its wood is potentially as practical for furniture and flooring as wood of other oaks. It also works very well as firewood. Historically, tanoak bark was useful for tanning leather, hence its name.

Although native and somewhat common in some coastal forests, tanoak is almost never a choice for intentional planting. Those that inhabit home gardens likely either grew from acorns, or were there prior to development of the landscapes. Young trees can grow fast to more than forty feet tall, typically with conical form. Mature trees might get twice as tall.

Tall trunks of tanoak are elegantly upright, and eventually develop lofty branch structure. Their gray or brownish bark is handsomely furrowed. The somewhat leathery evergreen foliage produces potentially objectionable tomentum. The dentate leaves are two to four inches long. Sadly, tanoak is very susceptible to Sudden Oak Death Syndrome (SODS).

Argyle Apple

Silvery foliage with fibrous brown bark.

Such silvery foliage provides a bold display on such a substantial tree. Most comparably silvery foliage is of smaller perennials or shrubbery, such as agaves or artemisias. Agyle apple, Eucalyptus cinerea, grows intimidatingly fast to nearly thirty feet tall and almost as wide. Although shorter than most other eucalypti, it can get a hundred feet tall in the wild. 

Paired juvenile leaves of young trees are circular and sessile (clinging directly to stems, without petioles). Unpaired adult leaves are lanceolate and as silvery as juvenile leaves. Coppicing or pollarding force juvenile growth and temporarily eliminate adult growth, but also ruin structural integrity. Trees subsequently rely on repetition of the same technique. 

Trunks and limbs can be disproportionately bulky, and create an illusion of a bigger tree. Irregular branch structure can be sculptural. Fibrous brown bark is handsomely furrowed. Juvenile foliage is a popular accessory to cut flowers. Adult foliage is likewise delightful. Incidentally, the Latin name of this species often transposes for Eucalyptus pulverulenta.

Palms Are Very Distinctive Among Trees

Palms provide distinctively lush foliar texture.

Palms seem to exemplify the culture of California. However, only the California fan palm, which is also the desert fan palm, is native. All others are exotic. With its dwarf palmetto, Oklahoma has as many native palms as California. Furthermore, the California fan palm is only endemic within remote riparian ecosystems of the Colorado and Mojave Deserts.

Common date palms were likely the first of the many exotic palms in California. Spanish Missionaries imported them for date production during the Eighteenth Century. Although initially utilitarian rather than decorative, recycled trees from displaced orchards became popular for larger landscapes. Potentially messy fruit is minimal without male pollinators. 

Long before urbanization displaced date orchards, many other palms came to California merely because of their visual appeal. Some are large enough to be shade trees. Others can provide shade in groups. Many develop elegant trunks or sculptural form. Some stay relatively low or shrubby. All innately provide famously and luxuriantly evergreen foliage.  

Palms are most certainly appealing within appropriate situations. They are very different from other trees though. Like arborescent yuccas and cordylines, palms are ‘herbaceous trees’. Unlike yuccas and cordylines, and with very few exceptions, palms do not branch. Nor do their trunks continue to expand in width as they continue to grow in height above.  

Palms consequently spend their first few years widening their bases at ground level. Big palms, such as Canary Island date palm, likely require many years. Once their bases are adequate, developing palms ‘launch’ into vertical growth. Although palms do not branch, a few, such as Mediterranean fan palm, develop multiple trunks from their primary bases. 

Once palms launch, they grow only upward. They lean only to avoid shade, or if pushed by wind. It is impossible to direct their bulky but singular terminal buds around obstacles, such as utility cables. It is also impossible to contain their shade as they get high enough to shade adjacent areas instead. Many palms are spiny, so are difficult to prune properly, even while young and within reach.

Red Ironbark Eucalyptus

The pendulous foliage of red ironbark eucalyptus moves softly in the breeze. The tall, curvy trunks are elegant and sculptural.

The many varied eucalypti never seem to outgrow the bad reputation of the blue gum and red gum eucalypti that get too big, messy and dangerous for urban gardens. Fortunately though, most others do not get nearly as large, and many stay proportionate to urban gardens. Their smaller canopies are neither as messy, nor as structurally unsound. Their adaptability to so many California climates and tolerance of aridity are serious advantages.

Red ironbark eucalyptus, Eucalyptus sideroxylon, is one of the mid-sized eucalypti that can eventually get quite tall, so is probably best where it has room to grow. Pruning for containment in compact gardens is actually quite a bit of work. Their coffee colored and deeply furrowed bark on elegantly sculptural trunks and limbs contrast nicely behind the mint frosting colored and softly pendulous foliage. The lanceolate leaves are about five inches long and three quarters of an inch wide. Flowers are almost always pinkish red, but can be pink or white.

Blue Spruce

Most blue spruce are garden varieties.

Sitka and Brewer spruce both live at low elevations and near the coast within their native ranges. Yet, neither perform as well here as blue spruce, Picea pungens, which is native to much higher inland regions of the Rocky Mountains. It grows neither as big nor as fast here as in the wild, so few old local trees are taller than thirty feet, or broader than twenty. 

Although compact, blue spruce should get sufficient space to develop its densely conical form without pruning for confinement or clearance. Such pruning is disfiguring. Since the evergreen canopy is so dense, it should retain low branches to the ground for as long as possible. Blue spruce works more like big and formal shrubbery than like compact trees.

Some cultivars of blue spruce are very stout and rounded. Most have remarkably blue or silvery color. Seed grown trees (which are not cultivars) are sometimes available online. They have potential to exhibit notable variation. Some might develop slightly more open canopies, with elegantly upwardly curved limbs. Spruce needles are about an inch long with quite a prickly texture.