Thursday, July 2, 2009

Broadleaved Evergreen Trees

I can't stay away from the topic of broadleaved evergreen trees. Deciduous trees are the default setting in the Northwest. Yet in places where there is little but pavement, cars, buildings and worse, we need the softening and color of foliage all the time. Though large expanses of deciduous forest or shrublands are lovely even in winter, a few trees along a downtown street or in a parking lot aren't enough to counteract the cold, gray harshness of an urban scene when they are leafless. We need foliage.

There are several arguments against broadleaved evergreen trees. The most reasonable one is that they block valuable winter sunlight. To avoid that, these trees should be kept away from windows, especially on the south, or trimmed high enough that the low winter sun reaches the window. Also, there are some evergreens with light canopies- laurel oak, for example- that let light through.

Others argue that broadleaved evergreens lose branches in our occasional heavy snows. It seems logical, but trudging through the extended snows of last December, I did not see an extraordinary number of leafy branches on the sidewalk and most broadleaved evergreen trees around here are no worse for wear. Those that had the most trouble with the snow had long, slender branches, especially loquats and magnolias. Pruning to shorten these limbs (which usually causes them to become stouter) can help.

Finally, there is the complaint that they aren't available. That's also somewhat true, especially if you need a large specimen. It's an extra cost to bring up trees from California or the South for a landscape project. If you can start smaller, several sources, including our nursery, Colvos Creek on Vashon Island, offer many broadleaved evergreen trees.


Here are some of the broadleaved evergreen trees suitable for Northwest landscapes:














Arbutus menziesii / MADRONE, MADRONA

One of our most alluring natives, this tree enchants with its peeling red-orange bark. Large, glossy leaves, fragrant white flowers and bright red fruits all on a beautifully sinuous framework add up to a stunning ornamental. Sadly, the tree is very hard to transplant, though it establishes fairly easily from nursery pots. Madrones need full sun and sharp drainage and can be killed by irrigation or fertlizer. Older trees have suffered in recent decades from various blights.





















Arbutus 'Marina' / HYBRID MADRONE

This newcomer is a hybrid of mysterious origin. It has foliage smaller than madrone, and showy pink flowers in fall-winter (or almost any time). Some trees bear huge orange-red fruits like those of strawberry tree (A. unedo). Bark is reddish, flaking. A small tree to 20-40 ft., 'Marina' has become popular in the Northwest, especially on streets. It wants sun and good drainage and is a good bet only in the warmer parts of the region.


















Azara microphylla / BOXLEAF AZARA

With tiny, glossy leaves on graceful, airy fronds, this Chilean beauty has many admirers. Its narrow outline and quick growth make it a great screen, even between buildings. Coming from forests, it is good in shade but takes sun well; it is quite drought hardy once settled. The frosting on this cake is the crop of puffy yellow flowers in February wafting a scent of chocolate and vanilla. The variegated form 'Variegata', with cream-edged leaves, is breathtaking.


Cornus / DOGWOOD


It surprises people to learn that there are evergreen dogwoods (and maples, pears, elms, ashes, etc.) These three really do stay green and are fine small trees for milder areas. All come from south and east Asia, where there is a swarm of related evergreen species.

















Cornus capitata / EVERGREEN DOGWOOD, HIMALAYAN DOGWOOD

This one stands out from the others because of its light green or grayish foliage and creamy yellow flowers. A small tree to 15-25 ft. tall, it sends its long branches artfully leaping and arching in all directions. These are covered in showy flowers that age strawberry pink over many weeks in late spring. Pink-red fruits, nearly golfball-sized, ripen in fall. Well worth a sheltered, partly shaded spot, this dogwood is hardier if raised from local seed, as ours are.


Cornus kousa v angustata / EVERGREEN KOUSA DOGWOOD

Most trees under this name are smaller, evergreen versions of the popular C. kousa. Their glossy leaves, silvery below, makes them fine foliage trees. That's good, because, so far, they have been shy flowering in the Northwest. The flowers they do produce are like those of the species, with creamy white, pointed bracts. Like the species, this variety is fairly drought-hardy.

















Cornus omeiensis / MT OMEI DOGWOOD

Seen mostly in the cultivar 'Summer Passion', this dogwood is a dense, rather narrow tree to 10-15 ft. so far. New foliage, produced most of the year, is copper red. Like the dogwood above, it is also shy to make flowers, which are smaller versions of those of C. kousa. With or without flowers, this tree is a fine screen plant or small standard tree for sun or shade. It seems hardy in all but the coldest zones west of the Cascades.






















Eriobotrya japonica / LOQUAT

A subtropical fruit tree with huge, leathery leaves seems an unlikely choice for the Northwest, but this Asian beauty is hardy in all the milder parts of the Puget-Willamette trough. There are trees 30 ft. tall in Portland and Seattle, and most specimens bear luscious orange fruit. Even without fruit, the foot-long, corrugated leaves make this an exotic standout. It is drought-hardy and adaptable to most soils.



Eucalyptus

These 500 plus Australian trees and shrubs have many admirers (and detractors in regions where they run wild). Their often picturesque forms and graceful, aromatic foliage combine with exotic colors in leaf and bark to produce a distinctive appeal. While most species are too tender for the Northwest, several have proven themselves here. All are very fast growing (3-10 ft. a year), drought-hardy and good in most soils, but they really need full sun.




















Eucalyptus archeri / ALPINE CIDER GUM

A slender tree to 40 ft. or more before developing a wider, rounded top. Small, egg-shaped to triangular leaves of deep blue gray line green twigs; bark is flaking brown over patches of red and green. Not the most exciting species, but nice when against a dark backdrop, and very hardy.





















Eucalyptus gunnii / CIDER GUM

Simiilar to E. archeri, with which it is easily confused. Cider gum tends to have pale, tan bark, white twigs and silvery leaves. It is renowned for hardiness, but is variable on that point. Most have survived recent decades here just fine. Some trees have reached 80 ft. or more.
















Eucalyptus pauciflora ssp niphophila / SNOW GUM

This is likely the hardiest species. Imagine a madrone, with its curvaceous lines, but with white, cream and gray trunk and narrow, blue leaves. Snow gums reach 30 ft. fairly quickly, then more slowly develop a broad, rounded crown to 50 ft. or more. They make choice landscape features.

Eucalyptus perriniana / SPINNING GUM

Grown also for its silver-dollar juvenile foliage, spinning gum becomes a small tree 30-50 ft. high with a broad, irregular crown of willowy, blue-green leaves on red or silver twigs. The tan bark of the trunk peels in sheets; branches are smooth, satiny olive-gray. The low, sprawling habit requires plenty of room, but the tree is very hardy.
















Eucryphia x intermedia 'Rostrevor'

This is the hardiest of the several evergreen species in this glorious genus of Southern Hemisphere trees. Sparkling, fine-textured foliage in soft billows cover its narrowly pyramidal form from head to toe. Fragrant white flowers resembling Hypericum open in summer. Growth is fairly fast and contented plants will reach 30 ft. tall. Such a first rate ornamental deserves wider use, though it is risky in the colder zones. It is best with partial shade and occasional watering.



















Ilex purpurea (I. chinensis) / ORIENTAL HOLLY

Holly is a bad word here in the Northwest, where English holly (I. aquifolium) is such a weed. This completely innocent species, however, is still rare and deserves wide use. No Christmas holly, it is a slender tree to 60 ft. tall with narrowly oval, bright green, completely spineless leaves 3-5 in. long. The soft, lustrous foliage is very cheering in gray winter light. Oriental holly seems drought-hardy and adaptable, happy for decades in the few spots locally where it has been planted.

















Laurus nobilis / BAY

This Mediterranean native is the bay of cooking. Its narrowly oval, dark green leaves are sweetly aromatic. They cover a broadly pyramidal form to 30-40 ft. tall. Some trees are very slow and haven't reached even 10 ft. in decades; others are that tall or more in five years. Bay wants good drainage, but grows well in sun or shade. It needs shelter in colder zones.



Ligustrum lucidum / GLOSSY PRIVET

A dense, rounded tree to 30 ft. or more, glossy privet presents a tailored and tony appearance. Crisp, glossy oval leaves are overtopped in early summer by lilac-like clusters of creamy white flowers. While very showy, these have the typical privet smell, which some people dislike. Tiny black fruits follow, which can lead to crops of unwanted seedlings. Snows have taken a toll on some privet trees in the past, but others have been unharmed. The tree takes drought but not temperatures below 10F.


Lithocarpus densiflorus / TAN OAK

Native in southwest Oregon and the mountains of California, this handsome tree is part oak and part chestnut. Its cream flower spikes, unpleasantly odor and all, resemble those of chestnut; the acorns in their bristly cups connect it to the oaks. Thick, 3-5 in. leaves , toothed and deeply veined, make up a narrow crown of horizontal to drooping branches reaching 100 ft. or more. This is a very worthy native, yet not much planted. It has unfortunately been the prime victim of sudden oak death, a bacterial disease that has wiped out many acres of forest in California, so many are reluctant to plant it. From the Willamette Valley north, which is well away from the infected areas, it shouldn't be a concern.


Continued next time

























































































































































1 comment:

  1. Hello Mike,
    I came across your blog while attempting to determine what is growing out of a Top Hat blueberry bush that came from a nursery in or around Woodburn, OR. I landed on your site because this is a fast growing deciduous, evergreen tree but we don't see this tree around here, Moscow, Idaho or at Moscow Building Supply where I bought the blueberry bush. This tree has grown at an alarming rate! It has gone from invisible to approaching the eves of a split level house in two years. It reminds me of Jack and the Bean Stalk with its rapid growth, but also the look of the leaves at the top. They are much bigger than the rest of the leaves. The leaves are not opposing(?), i.e. they are not opposite one another and are too long to be poplar or cottonwood leaves. I wish I could send a picture. I really like this tree and hope to successfully move it to a new location, but it would help to know what it is. It survived our cold winters with some week long cold spells going down to zero. Any ideas?

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