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Norfolk Island Pine

Norfolk Island pine seems to have been built rather than grown.

            In coastal areas of Southern California, the Norfolk Island pines, Araucaria heterophylla, are among the most distinctive large trees. Perhaps they are better described as ‘unusual’ . . . , or even ‘strange’. They are so symmetrical that they seem to have been assembled from prefabricated kits than to have grown as natural trees. Their strictly organized conical branch structures and remarkably straight central trunks are always visible through their uniformly open canopies. In such mild climates, they can get nearly a hundred feet tall and half as wide, so are not easy to hide. In Hawaii, their symmetry has actually made them popular as Christmas trees. Their finely textured juvenile foliage is comprised of narrow, half inch long pine-needle like leaves, which are wider among adult growth.

            Locally though, Norfolk Island pines are primarily enjoyed as houseplants, particularly since they can grow slowly and live in pots for many years. The climate is just a bit too cool in winter for them to be very happy in the garden. However, as they eventually get too large for their homes, many end up in the garden anyway. They stay much smaller and are not nearly as symmetrical as they are in milder climates, and may be damaged by the more severe frosts every few years, but they have a certain appeal and distinction regardless. Those that get planted in the garden while young seem to be more symmetrical than those that get disfigured by living as houseplants longer. For some reason, trees that develop weak or curved trunks as houseplants tend to continue to grow with interestingly irregular trunks and branch structure.

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White Alder

White alder has a distinctive silhouette.

During the summer, the native white alder, Alnus rhombifolia, is a nice shade tree that looks bigger than it really is. By late winter, the bare deciduous canopy has an appealingly picturesque silhouette. This time of year is actually when white alder is typically less appealing, with dead foliage that provides no interesting fall color, but lingers until knocked down by rain or late frost. Yet, even now, it sometimes surprises with these funny looking floral structures that are interesting both in the early winter landscape, and with cut flowers.

In past decades, white alder was an ´expendable’ tree that was put into landscapes for quick gratification while slower but more desirable trees matured. By the time the desirable trees matured, the alders were removed to make more space for the desirables. This technique was practical because, like many fast growing trees, alders do not live very long, so start to deteriorate after about twenty five years anyway. However, alders often live longer than expected.

Mature alders are usually less than fifty feet tall where they are well exposed. They can get at least twice as tall where shaded by other trees or big buildings. Their plump trunks with mostly smooth silvery gray bark make them seem larger than they really are though. Too much water promotes buttressed roots which can displace pavement.

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European White Birch

European white birch exhibits elegant trunks.

European white birch, Betula pendula, is a team player. It usually inhabits landscapes in groups rather than singly. Some trees have two, three or more trunks. After all, its primary allure is its strikingly white trunks. Because its foliar canopies are not overly broad, a few can fit into limited space. It is an informal and relaxed tree with nicely pendulous growth.

Mature European white birches are not much more than fifty feet tall here. They can grow taller where winters are cooler. Their slender trunks are mostly less than a foot and a half wide. They generally lean with prevailing winds and away from shade. Their smooth and white bark develops rough and black furrows with age. Their little leaves are deciduous.

European white birch appreciates regular irrigation, so should perform well within lawns. It produces only moderate shade. ‘Laciniata’ has intricately lobed foliage and a narrower form. ‘Youngii’ is so pendulous that it needs staking to stand upright. It can not grow very tall. ‘Purpurea’ has bronzed foliage and somewhat tan trunks, but has become very rare. European white birch might self sow.

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Bark Up The Right Tree

Bark can contribute color and texture.

Autumn foliar color does not seem to last long enough. As it dissipates, though, it reveals silhouettes of bare deciduous trees. Some are delightfully sculptural, with strikingly pale bark on their trunks and stems. Others develop distinctively reddish twigs. Some display interesting bark textures or patterns. Color, texture and patterns are remarkably variable.

Of course, for most species, bark does not change much throughout the year. It becomes more prominent now merely because defoliation increases its exposure. In fact, some of the most distinctive bark belongs to evergreen species. Some belongs to flowering trees, fruiting trees or arboriform shrubbery. The sources are as variable as the characteristics.

European white birch is likely the most familiar tree with white bark. Jacquemontii birch is even whiter. California sycamore is a massive tree with mottled light gray and tan bark. Crape myrtle, which is more proportionate to home gardens, is more mottled. Some elms exhibit elegant tan trunks and limbs. European beech trunks develop metallic gray color.

Melaleucas are evergreen trees with distinctively shaggy trunks. Eucalyptus are likewise evergreen, but generally with pale and smooth trunks. Lemon gum is particularly tall and elegant. However, red ironbark eucalyptus has dark and notably rough trunks and limbs. ‘Marina’ madrone develops smooth trunks and limbs with brown and cinnamon red color.

Coral bark Japanese maple and osier dogwood display colorful bark differently. Theirs is on small twigs rather than trunks and main limbs. Color actually develops in response to autumn chill and defoliation. Coral bark Japanese maple develops, pinkish orange color. Osier dogwood is more brownish red, although some cultivars are orangish or yellowish.

Trees that exhibit distinctive bark are subject to the same constraints as all other trees. In other words, they must be appropriate to their particular landscapes. California sycamore for example, is much too large for compact urban gardens. Osier dogwood can grow as a thicket without intensive maintenance. Any new tree or shrubbery should be sustainable.

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The Importance of Proper Arboriculture

Arboriculture is horticulture of trees.

Pasadena sustained the worst of the damage caused by the strongest Santa Ana Winds in three decades. Huge piles of debris from broken trees are much more than can be removed any time soon. Falling debris and trees damaged many roofs, cars and anything else that happened to get in the way.

Other towns and neighborhoods throughout the area, particularly those at the base of mountains, also sustained major damage. At the same time, severe winds ravaged the San Francisco and Monterey Bay Areas as well, particularly in the Santa Cruz Mountains and the hills of the East Bay.

Some of the damage caused by wind in urban areas might have been less disastrous if trees had gotten the respect and attention that they deserve. Some trees develop structural deficiencies that need to be corrected by pruning, either to eliminate the problems, or at least to decrease the strain exerted onto the structurally deficient parts. A few trees that become unstable as they mature may likewise need to be pruned or even removed.

It is not always possible to prune trees to remove all structural deficiencies without damaging the affected trees more, or causing more structural problems to develop. For example, major pruning to remove all parts that may get blown down by wind, such as pollarding or ‘topping’, may seem to be effective for the short term, but actually stimulates the development of vigorous secondary growth or watersprouts that are disproportionately heavy and even more likely to tear off from the older limbs.

Structural pruning more often involves thorough reduction of weight and wind resistance. Weight of foliage and stems directly applies leverage against unions where smaller stems are attached to the larger stems from which they originate. Wind resistance adds more leverage as foliage gets blown about by wind. Thinning obviously removes significant weight, and also decreases wind resistance to allow wind to blow though the affected canopies.

Besides helping to compensate for structural deficiency, structural pruning is also beneficial to potentially unstable trees for the same reasons. However, unstable trees typically need even more reduction of weight and wind resistance. Some of the most unstable trees and those that are deteriorating need to be removed because their instability cannot be accommodated.

During winter, while deciduous trees are bare, evergreen trees are more susceptible to wind damage, obviously because they retain their weight and wind resistance through winter while the weather is the most severe. Unstable trees become even more destabilized as rain softens the soil. Regardless of the potential for susceptibility to wind damage, this would be a good time of year to get any needed tree maintenance done, prior to any more windy and rainy winter weather.

Arborists certified by the International Society of Arboriculture are the most qualified to identify potential structural problems or instability, and to prescribe corrective procedures. A list of certified arborists can be found at the website of the International Society of Arboriculture at http://www.isaarbor.com.

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Trees May Benefit From Winterization

Many trees need no winterization pruning.

Arboriculture becomes more of a concern at this time of year. Although winter is a month away, the weather is becoming increasingly stormy. Wind and rain can dislodge limbs or destabilize entire trees. Some trees may benefit from winterization prior to even stormier weather in the future. Some may need the specialized services of professional arborists.

Dormant pruning of deciduous fruit trees is, incidentally, not the same as winterization. It happens later in winter, after the subjects have been dormant for a while longer. Besides, after proper dormant pruning last year, they should not need winterization now. However, if subjects are defoliated, they should not mind early pruning. They are already dormant.

Ironically, the trees that are more likely to require winterization are evergreen. Deciduous species perform almost all of their own winterization naturally. They defoliate to eliminate most of their resistance to wintry winds. In other words, they become more aerodynamic. Defoliation also eliminates most of the surface area to accumulate heavy water from rain.

Evergreen species are generally more resilient to wind than foliated deciduous species. However, as deciduous species defoliate, evergreen species can not. Evergreen foliage therefore becomes less aerodynamic and more vulnerable to wind. Also, it absorbs more heavy rainwater. The added weight of rainwater causes limbs to sag and perhaps break.

Rain does more than cause foliage to become heavier. It also saturates soils, which can potentially compromise root stability. The timing could not be worse, since wind typically accompanies rain. This is also more of a problem for evergreen species than deciduous species. However, some storms arrive early, and some deciduous species defoliate late.

Winterization pruning is as variable as the trees that benefit from it. Large trees will likely need specialized services that only arborists can provide. Japanese maples may require only minor clipping of stems that have extended too far. Many trees require nothing at all. Ultimately, such techniques should help limbs and trees survive eventual wintry weather.

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Freeman Maple

Red maple combines with silver maple.

It combines the autumn foliar color of red maple with the lacier foliar form of silver maple. Freeman maple, Acer X freemanii, is a hybrid of the two. It occurs naturally where ranges of its parents overlap. However, most modern garden cultivars are products of intentional hybridization. Like silver maple, it does not need much chill to exhibit autumn foliar color.

Freeman maple inherits other attributes from both its parents. It combines rapid growth of silver maple with structural integrity of red maple. Although it gets bigger than red maple, it is not as imposing as silver maple. It develops high branches like silver maple, but also is symmetrical like red maple. Big roots are about as complaisant as those of red maple.

Mature Freeman maple trees can grow about forty feet tall and broad. Autumn foliar color is vivid orange and red, and lasts longer than that of red maple. Since Freeman maple is a hybrid, it is mostly sterile. It can not generate an annoying abundance of seed. Nor can it naturalize in favorable climates. It is an exemplary maple for mild climates such as this.

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Norway Maple

Norway maple looks like a sycamore.

It is rare now, but Norway maple, Acer platanoides, was once common as a street tree. A few are prominent within neighborhoods that were developed in the 1950s and 1960s. It resembles the common London plane. In fact, its botanical name translates to ‘maple like a plane tree’. Unfortunately though, the roots are perhaps too aggressive with pavement.

Norway maple defoliates somewhat more efficiently than London plane tree. However, in spring, it refoliates significantly later. Otherwise, it is a splendid shade tree. A few modern cultivars exhibit bronzed foliage that yellows for autumn. One exhibits variegated foliage. Another has chartreuse foliage. ‘Schwedleri’ was once the most common bronze cultivar.

Very few Norway maples are taller than forty feet within the mild climates here. They can grow significantly larger in cooler climates, such as the Pacific Northwest. Their palmate leaves are about five to nine inches wide. New trees are rarely available from nurseries, so require special ordering. Norway maple is not overly discriminating in regard to soils. It prefers regular irrigation through summer warmth.

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Valley Oak

Valley oak is a stately tree.

Native trees are not necessarily the best options for home gardens. Valley oak, Quercus lobata, for example, grows much too large. Old trees can grow more than a hundred feet tall. Although unpopular for new plantings, it sometimes self sows. Also, new landscapes sometimes develop around old trees. Formerly rural trees therefore become urban trees.

Old trees are unfortunately very sensitive to disruption of their surroundings. Grading can severely damage their shallow feeder roots. Irrigation to sustain new landscapes is likely to promote rot of older and larger roots. Trees that should live for centuries can succumb to such damage within decades. Younger trees are fortunately adaptable to landscapes.

Nonetheless, young valley oaks are trees for future generations. Also, they require plenty of space. Although it may take a few centuries, trunks can eventually grow ten feet wide. As they mature, such big trees can make a big mess. The deciduous foliage can shed for weeks instead of days. The pale yellowish brown autumn foliar color is rather mundane. Without excessive irrigation, roots are remarkably complaisant.

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Firewood Literally Grows On Trees

Tree maintenance produces most urban firewood.

Autumn foliar color is a reminder that, regardless of pleasant weather, it really is autumn. The days are getting shorter. The weather is getting cooler. Households with operational fireplaces or wood stoves may resume using them. Firewood will therefore become more of a desirable commodity. A few trees might require pruning for clearance from chimneys.

Only several decades ago, firewood was much more popular than it is now. More homes that were modern for their time featured fireplaces. Other options for heating, such as gas and electricity, were relatively more expensive. Firewood was still more readily available from nearby orchards, farms or forests. Air pollution was not such a concern like it is now.

Almost no modern homes feature fireplaces now. Modern building codes in most regions disallow installation of fireplaces or wood stoves. Gas and even electric heating systems are more efficient than in the past. Many orchards and forests that provided firewood are now gone. Not many who inhabit houses with fireplaces have time to cut and split wood.

Besides, fireplaces and wood stoves lack thermostats or any method of regulation. They also generate considerable volumes of ash and are messy to clean. Enough firewood for the season occupies significant space in a garden. Then, firewood must be brought in to the fireplace or wood stove. It is no wonder that modern heating systems are so popular.

Nonetheless, firewood is not completely obsolete. It is a renewable resource that literally grows on trees. Many tree service businesses sell mixed firewood as a byproduct of their work. Ideally, they prefer to leave it where they perform their work, for whomever wants it. Woodcutters provide specific types of firewood from private forests, or perhaps orchards.

By now, firewood for this season must be seasoned, or completely dried. Otherwise, it is difficult to ignite, burns inefficiently, and produces excessive smoke. Wood that is still too fresh will be ready to burn for the next season. Although wood can eventually rot outside. Palm, cordyline and yucca trunks burn too fast without enough heat to work as firewood.