Tree of the Week: The picturesque Aleppo pine

Aleppo pine -- Pinus halepensis

Tough and rugged as a movie outlaw, the Aleppo pine's asymmetrical shape, leaning habit, sparse foliage, haphazard branching pattern, and grayish branches and needles contribute to a picturesque image. But it isn't a pretty pine tree.

Native to coastal areas around the Mediterranean basin, the tree historically was more abundant on the west side (Spain, Morocco, Algeria) than around the Middle East, even though its name derives from the Syrian city of Aleppo. It thrives on thin soil and steep slopes, and prefers deserts and seacoasts, where it develops into twisted and bent shapes.

The tree produces copious, pungent sap, called resin, that has been used for millennia to embalm Egyptian pharaohs and transform Greek wines into retsina. Resin of all pine trees also has a long history of use for medicinal purposes, skin treatments and herbal steam baths. The sacred tree of the solar god Attis, temple-close Aleppo pines were decorated for the winter solstice festival as a kind of pre-Christian Christmas trees.

In the late 1800s, the tree was widely planted by early settlers of the Western U.S. It makes a good shade tree in the desert, but in the Southland we use it as an ornamental, often plant it in lawns and so overwater and overfeed it that it sometimes drops a water-soaked branch.

Moderate to fast-growing even in poor environments, the Aleppo pine grows 30 to 60 feet tall and 20 to 40 feet wide. It is an irregularly shaped, open-crown evergreen tree with ascending branches that will live for 150 years. The trunk is lined with silvery gray, orange-dotted, vertical flakes, but the bark is more deeply furrowed near the ground.

The needles are 2.5 to 4 inches long, grayish-green tinted and come in bunches of two, rarely three; they face upward in the varieties sold here. When they fall to the ground, the needles make a highly combustible litter. Flowers are inconspicuous; female flowers develop into narrow 2- to 3-inch-long green cones, which ripen to a red-brown color over a 24-month period. The tree is drought tolerant, takes any soil and wants full sun. Roots can be invasive.

The tree has few pests; the main one is a tiny spiderlike mite of the genus Oligonychus, which causes Aleppo pine blight, a nonlethal affliction in which needles turn brown and die in fall or winter, to be replaced by new ones in spring. Since the Aleppo pine grows where few other trees would, it is an important timber tree in Northern Africa and the Middle East, even if the wood isn’t particularly valuable.

-- Pieter Severynen

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Photo: Pieter Severynen

Tree of the Week: Beefwood so named for its red sap and wood

 

Coast Beefwood -- Casuarina stricta

From a little distance the coast beefwood looks like a feathery pine tree. Cone-like fruits on female trees heighten that impression. But close up, the long green "needles" turn out to be small, segmented twiglets, whose one-quarter-inch-long pieces may be pulled apart at the joints, just like the familiar horsetail plant. The common name for this Australian native comes from the red sap and reddish hardwood; the tree is also known as drooping she-oak.

Casuarinas are tough, fast-growing trees that take seacoast, poor soil and windy conditions, but some species such as the river she-oak, C. cunninghamiana, and especially the horsetail tree, C. equisetifolia, become aggressively invasive where introduced in moister climates and kill off surrounding vegetation with their abundant litter. Symbiotic bacteria in their root nodules fix nitrogen for the trees to use.

The coast beefwood is an evergreen tree that reaches 20 to 35 feet tall and may become as wide. As a street tree it may be pruned into whatever shape fits the space. The bark is gray, rough and furrowed, but not deeply so. A whorl of inconspicuous little triangular leaves, looking like tiny teeth, surrounds each joint, but the green twiglets have taken over the leaves’ photosynthesis function. The number of leaf teeth can be used to distinguish the species: about 11 for the coast beefwood and seven for the horsetail tree. Male and female flowers grow on different trees. Male flowers are dangling catkin-like spikes. They produce such abundant brown pollen while in bloom that the whole tree looks rusty at that time. In contrast, the female trees stay green looking; they produce dark woody cone-like fruits about an inch in size. The tree is drought resistant and  takes most any soil but wants full sun.
 
--Peter Severynen

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Photo: Peter Severynen

Tree of the Week: The brilliant-colored eucalyptus

Mindanao gum -- Eucalyptus deglupta 

Streaks of brilliant colors -- red, purple, yellow, blue, green -- are splashed across the trunk of this eucalyptus, which also goes by the name of rainbow eucalyptus. The Mindanao gum is one of the few non-Australian eucalypti. It is native to tropical rainforests in the Philippines, Indonesia and Papua New Guinea and named for the Philippine island of Mindanao. As such it likes regular water and cannot take drought. That and the usual eucalyptus ills of our area make it unlikely for it to be planted much anymore here, but its colorful decorations make it a prized specimen where it does occur.

The tree is grown in tropical areas for pulpwood production for paper and harvested at an early age. Sometimes it is allowed to develop for construction lumber, but the wood is only moderately strong and not durable.

The Mindanao gum is a fast-growing, rather open, erect evergreen tree that may reach a height of 75 to 200 feet and a width of 30 to 75 feet. The smooth bark peels off to display the bright colors underneath. The oval, 6-inch-by-3-inch leaves are bright green. They contain only a little aromatic oil.

The tree may bloom when it is 2 years old. Flowers are clustered together and not very conspicuous. When in bud the white to pale yellow stamens that give blooming flowers a fluffy look are hidden in a covered cap, known as an operculum. The stamens push this cap off at flowering. The genus name, based on the Greek eu kalyptos, or well-covered, refers to this hidden quality. Woody cone-shaped capsules appear after flowering.

The Mindanao gum will take a wide variety of soils, but likes full sun. It is frost hardy down to 24 degrees Fahrenheit. Just like other eucalyptus trees, it is susceptible to aphid-like psyllids and borers.

The genus Eucalyptus was named by the 18th century French botanist Charles Louis l’Heritier. The tree is part of the myrtle family, or Myrtaceae.

--Pieter Severynen

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Photo: Pieter Severynen

Tree of the Week: The purple-leaf acacia

Purple-leaf acacia -- Acacia baileyana "Purpurea’"

The purple-leaf acacia is unapologetically not green. Many people love it while others find its soft, silvery blue-gray foliage tinged with purple too intense for their green garden color scheme. The Bailey acacia, either in purple-leaf or plain-gray variety, is also known as mimosa for the fragrant, tiny, yellow flower pompoms that appear all over the plant at the end of winter. They are often sold in small bouquets as harbingers of spring in sun-challenged climates.

This acacia is a member of the legume or pea family that manufactures its own nitrogen fertilizer. It originated in southeastern Australia where it goes by the name Cootamundra Wattle. In Australia, it has a tendency to naturalize beyond its native habitat, so it is looked at with some suspicion here, but unlike some other acacias, the purple-leaf acacia (at least for now) is not on the Cal-IPC invasive-plant watch list. The genus name refers to the fact that many acacias are thorny, while the species name honors the Australian botanist Frederick Manson Bailey. 

A moderate-to-fast-growing small evergreen (evergray?) tree, the purple-leaf acacia reaches 20 to 30 feet tall and wide. Its dense, spreading canopy is easily shaped as a single- or multi-trunk tree. The tree is short-lived and may last less than 30 years, which makes it ideal for a short-term landscape. The bark is smooth gray and its branches are somewhat weeping. Its leaves are small and compound, like tiny feathers. The purple sheen is most pronounced on new leaves, so its branches are occasionally pruned back to stimulate new growth. Prominent stamens define the tiny, soft, bright yellow flowers that are grouped in clusters. Easy to grow, frost-hardy, drought- and disease-resistant and seaside-tolerant, the tree likes full sun to filtered shade and accepts most types of soil. It has non-invasive roots.

The purple-leaf acacia is often planted on hillsides. It has a tendency to look a little wild. Its appearance is better when  it is kept somewhat open, with some branches removed all the way back to the trunk. The tree is very popular in the San Francisco Bay Area.

-- Pieter Severynen

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Photo credit: Pieter Severynen

Tree of the Week: That banana is really an herb, not a tree

 

 The Banana Tree – Musa acuminata

For a tropical plant, the banana tree is amazingly at home in the Los Angeles area: not only does it grow here, after 10 to 15 months of frost-free conditions it actually produces a flower stalk and edible fruit (Sunset zones 21-24 and some below). Its huge leaves convey a tropical look and indicate that serious frost (below 28 degrees F) seldom or never occurs at that location.

The first bananas were known more than 2,000 years ago in Southeast Asia, centered on the Malaysian peninsula; they were inedible, seeded fruits, but crossing produced seedless, edible or cooking varieties which ripened to red or green fruits. Like many fruit trees the plant has a tendency to produce mutations or "sports." In 1836 the Jamaican Jean Francois Poujot discovered a sweet yellow mutant strain in his orchard, the now familiar dessert fruit; it was introduced to this country in 1876. The California Rare Fruit Growers indicate that some 10 varieties are grown here locally; worldwide the number of cultivars is in the hundreds. 

A giant perennial herb rather than a tree, the banana plant grows quickly from underground rhizomes (rootstocks) into a 10 to 25 feet tall and wide plant, depending on variety, with dwarfs half the size of regular trees. The trunk (pseudostem) consists of leaf sheaths wrapped around each other. Many suckers come up from the roots, but only one should be allowed to remain, to replace the fruiting trunk after bearing. Large elliptic green or purple leaves can grow as huge as 9 feet tall and 2 feet wide; protect them from wind if you like to see the leaves whole and the tree standing up straight.

A reflected heat location next to a south wall or a driveway makes for tastier fruit, as does placement at the top of a slope (cold air flows downward); on the other hand the tree may require some afternoon shading to prevent sunburn. The enormous flowerstalk first grows upward, then down; it carries clustered rows of white flowers, covered with purple bracts on the outside. The first 5 to 15 rows are female; later rows centered near the end of the stalk carry sterile male and female parts. The female flowers develop without pollination into clusters of fruits, called hands; each fruit may be from 2½ to 12 inches long and three-quarters to 2 inches wide. Ripening may take eight months.

The trees want full sun and most any soil as long as it is very rich (an old compost pile is great) and lots of water, but no overwatering. In contrast to the tropics they suffer from few pests here: scale, aphids and sooty mold, which can be prevented by controlling ants in the tree.

Several ornamental species of banana are found in the genera Ensete and Musa.

--Pieter Severynen

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Photo: Pieter Severynen 

Tree of the Week: A cedar with annual color changes

 

The plume cedar -- Cryptomeria japonica elegans

First-time viewers sometimes wonder if the plume cedar they are looking at is sick or dying when they see its mahogany or copper-purplish hues. But they need not fear: It is a temporary condition brought on by low temperatures.

The plume cedar is an unusual variety of the Japanese cedar that never sheds its attractive juvenile foliage and goes through annual color changes wherever temperatures drop low enough. The fast-growing cedar, Japan’s national tree, which is known as Sugi there, may tower to over 200 feet. It is a conifer related to and somewhat resembling the giant sequoia tree, but without the thick and spongy bark. But the relatively small plume cedar is a diminutive family oddity, completely unlike the species, and is valued as a beautiful smaller conifer. The tree does best in colder and wetter climates but the tree has high drought tolerance. The Southland is about its southern limit.

The evergreen grows slowly into a dense, fine-textured, symmetrical pyramid of about 20 feet tall by 10 feet wide, although it may slowly keep on increasing in height and width. On older trees the trunk may lean or curve. Branches hang down slightly. Thin reddish-brown bark peels off in strips, especially on old trees. Soft and feathery awl or needle leaves are less than 2 inches long and are green to bluish-green during most of the year. Flowers are inconspicuous and the tiny brown cones are about a half-inch to 1 inch in size. The tree likes full sun, tolerates a wide variety of soils and reportedly will grow in compacted soil. There are no surface root problems, but the leaves are sensitive to leaf blight and leaf spot.     

The tree is sometimes planted in groves, as in the photograph above, or some branches may be pruned out. Several dwarf varieties are available.
 
--Pieter Severynen

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Photo: Pieter Severynen

Tree of the Week: The Welwitschia: Small, old, odd

The Welwitschia – Welwitschia mirabilis

The Welwitschia (well-WIT-shia) may well be the oddest tree in the world. It produces only two, strap-shaped leaves, which for its 500- to 2,000-year-long life keep on growing from the base and dying from the top. Its trunk rises only a foot or so above the soil surface and stays there, but keeps getting wider every year.

While it is cone bearing, it does not completely belong in one of the two main groups of plants -- the gymnosperms (cone-bearing trees with naked seeds, softwoods), or the angiosperms (flowering trees, with covered seeds, hardwoods) -- but has characteristics of both.

The Welwitschia originated in the extremely harsh, dry and windy environment of the Namib Desert of Angola and Namibia in southwestern Africa. There, the mixing of cold ocean current with hot desert air produces dense fog every morning. Microscopic leaf hairs take in most of the plant’s water from the morning fog. Its stomata, or leaf holes, close in daytime to prevent exhaling moist air, but open at night and in the cooler hours, during which time they inhale and store the air’s carbon dioxide for processing during the heat of the day. Our Southland climate is hospitable to many trees from all over the world, but does not duplicate fog desert conditions, so you will not see the tree outdoors in Los Angeles. However, many people grow it indoors, which is not that hard to do, and you may find it in botanical gardens.

The tree grows ever so slowly until it resembles a huge woody carrot with a grayish-brown flattened top on a short, fibrous above-ground stem with corrugated bark. The leaves are implanted around the top of the trunk. The tallest one reaches 5 feet; the fattest trunk is 10 feet wide. Roots, including the thick taproot, may go 90 feet down. There are no branches. The thick leathery evergreen leaves keep growing from the base, but split lengthwise and then partially curl and bunch up, so that there appear to be many more than 2. The leaves channel the fog to the roots. Male and female flowers are borne at the top of the trunk, on different plants. The larger female cones are blue-green, the smaller and less cone-like males are salmon-colored, small and oblong. Unlike other cone-bearing plants, they depend on insects for fertilization.

Austrian botanist and medical doctor Friedrich Welwitsch, who was employed by the Portuguese government, "discovered" the plant in 1859. Its descriptive South African name is tweeblaarkanniedood (two leaves cannot die). Oyanga, the local Herero name, means onion of the desert and is said to refer to the tasty stem.

--Pieter Severynen

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Photo: A relatively young plant with a female cone. Credit: Pieter Severynen

Tree of the Week: Do we need to help nature recover from fires?

Although the Station Fire is fresh in our minds, it is almost a year since the Sayre fire burned in the Sylmar area last November and a little over two years since the May 2007 Griffith Park fire.  Our original native landscape, be it sagebrush, chaparral or woodland, is adapted to periodic fires occurring at intervals of 25 to 100 years and doesn’t need our assistance to recover. As much as we love to help nature, she does quite well on her own. Buried seeds of native annuals and perennials will sprout but, exciting as it is to see wildflowers come up during the first spring and the gradual changes thereafter in the landscape, the recovery of mature brush and perennials will take many years. Even the resident animals will gradually return. Human fire recovery efforts, such as seeding slopes with nonnative grass, have usually done more harm than good.

It is a different story in the natural places we have steadily interfered with or live very close to, the wildland-urban interface, for example, at the edges of the Santa Monica or San Gabriel mountains. Heavy rainfall the first winter may cause the erosion of slopes and trails without leafy branches to break the force of the rain or enough surface roots to hold the slope in place. Wooden retaining structures may have become partially burned and lost their stability. Trees may have become dangerously unstable or be leaning and will have to be cut down to protect hikers. Fires occurring too close together, within a few years of each other, will permanently wipe out native plants. In many places the fires weren’t hot enough to kill the seeds of invasive plants; those sprout first, causing major infestations of obnoxious weeds including black mustard, castor bean, thistles and grasses such as annual ripgut, fountain and Pampas grass. Those weeds will crowd out the native plants. Some of our nonnative garden trees and shrubs also spread their seeds and become post-fire invaders, such as fig, pepper tree, eucalyptus, Mexican fan palm, broom.

So should man help nature recover from fire? Yes, but only as appropriate. In some wildland-urban interface areas, once it is safe to go back in, we should judiciously interfere through eradication of weeds, prevention of erosion, restoration of trails and the planting and maintenance of appropriate natives.

Although resources are available to fight fires, there is very little money for preventing the next fire or restoring nature. To find out more, help or volunteer, check out the Safe Landscapes Calendar or any of these websites: northeasttrees.org; angeles.sierraclub.org; treepeople.org; cal-ipc.org.

--Pieter Severynen

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Photo: A tree damaged in the Sayre fire. Credit: Pieter Severynen

 

Tree of the week: Incense cedar

The (California) incense cedar -- Calocedrus decurrens

This narrow columnar evergreen with a manicured look stands out from the crowd with its flat sprays of tiny, bright, apple-green leaves, completely different in color from surrounding trees.

The California native incense cedar, whose sap releases the odor of incense, is a great demonstration of how unique shades of green can be. This member of the cypress family grows best in the mountains from southern Oregon to Baja California. There it receives more water than in the Southland flatlands, but it is remarkably climate adapted and drought resistant. The incense cedar, which can live to 500 to 1,000 years, is best known as a good source for pencil wood.

Slow to start, an established incense cedar in the right environment may grow up to 2 feet a year to a dense, symmetrical, cone-shaped tree of 75 to 90 feet, but only 10 to 15 feet wide at the base in its native areas. In the garden it may reach only half that size.

Without other trees close by, the lower branches and leaves will hang on forever. In a shaded forest environment the trunk will be bare. There eventually the trunk may attain a diameter of 10 feet. Its fibrous and deeply fissured bark is orange brown.

Fine in sun or part shade and happy with many soils, in our lowlands the tree looks best with occasional summer watering. Tiny scale-like leaves, in whorls of four, cover twigs that grow as flattened sprays. Inconspicuous flowers are followed by small, hanging, yellowish brown cones that open like duck bills when ripe. No pruning is needed, and there are no root, litter or pest problems.   

In the garden the incense cedar, formerly known as Libocedrus, is used for screens, hedges and windbreaks. It is well known to Northern European gardeners and our cool summer neighbors to the north, but it is less frequently used here. Columnaris and Compacta indicate the nature of these cultivars, while Aureovariegata has interspersed sprays of bright yellow foliage.

-- Pieter Severynen

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Photo: Pieter Severynen

Tree of the Week: The bonuses of birch

The European White Birch -- Betula pendula

For thousands of years our ancestors from colder areas in Europe and Asia have used a treasure trove of gifts from the everywhere occurring European White Birch. They made canoes with its almost indestructible papery bark, fermented the sugary spring sap into beer or wine, brewed tea from its leaves, shampooed their hair and tanned their leather with its various extracts, danced around a skinned May pole trunk during fertility rites, "birched" the bottoms of their unfortunate children with bundles tied from its branches (not the tree’s fault) and stoked their fires with its hot burning wood. Pharmaceuticals extracted from the bright white bark may bring us even more presents in the future.
 
We get introduced to this beautiful tree in Grimm Brothers fairy tales or Disney movies, we love it for its lacy appearance, white bark and yellow fall color and we keep planting it here although it prefers cooler places over our warm and summer dry climate.

The deciduous European White Birch grows at a moderate pace to 30-to-40 feet tall and half as wide; its life may stay short of the half century mark. Main branches are upright, side branches weep. Eventually the whole tree assumes a weeping character, more so in some varieties than in other ones.

On young twigs the bark is smooth and golden; in later life it becomes bright white and is punctuated by horizontal brown lenticels (breathing pores), until it finally turns black and furrowed at the base of the trunk. The bark peels off in thin strips.

Diamond shaped, 2½-inch long, toothed, glossy green leaves end in a tapered point. Inconspicuous male flowers are clustered in tight, yellowish brown, hanging catkins of up to 2½ inches long. Female flowers are arranged in upright, greenish catkins half that size. They are followed by drooping, soft, cone like fruit that disintegrates into small seeds in late summer.

This tree looks sad without regular water. It prefers full sun to part shade. It will live in uneasy alliance with lawns, where surface roots may develop, but it does better without competition. Unavoidable aphids will drip their honeydew secretions on the ground below; to avoid borers it is best to limit pruning as much as possible.   

Many varieties exist within the species, from dwarf to narrow upright and purple leafed. Other species are worth considering. The wood has a beautiful, satiny sheen, but is only good for indoor applications. The tree is a member of the Betulaceae or birch family, which includes alder (Alnus) and hornbeam (Carpinus). 
   
 
--Peter Severynen

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Photo: Peter Severynen