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.
It may not seem like much to take notice of. Sweet olive, Osmanthus fragrans, resembles glossy privet, but is neither as glossy nor quite as richly green. The dense and evergreen foliage can work about as well for a formal hedge though. It is even better as a small and billowy tree. It gets at least as high as ground floor eaves, and can reach upstairs eaves.
The primary allure of sweet olive is its delightfully pervasive and fruity floral fragrance. Its small and slender clusters of tiny pale white, yellow or gold flowers are mostly obscured by foliage. For those who are unfamiliar with it, the fragrance might be difficult to identify. Bloom is most abundant before and after summer. Sporadic bloom happens at any time.
Because sweet olive is more olfactorily appealing than visually appealing, it works quite nicely as in informal hedge behind prettier plants. It can stay narrow between windows of neighboring homes that are a bit too close together. If enough flowers are available, they might flavor tea and confectionery. A cultivar with variegated foliage is unfortunately rare.
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.
Even if never as overly indulgent in bloom as when new, Kalanchoe blossfeldiana is one of the more sustainable of popular blooming florist plants. Forced bloom remains colorful for quite a while. By the time it deteriorates enough to necessitate grooming, new foliage may already be developing. Sporadic subsequent bloom is more natural in appearance.
Ultimately, Kalanchoe blossfeldiana becomes more of a succulent foliar houseplant that occasionally blooms, rather than a spectacular floral plant. Individual plants may survive for only a few years, but are likely to generate basal pups that grow as new plants during that time. Also, they are very easy to propagate by succulent stem and even leaf cuttings.
Mature Kalanchoe blossfeldiana do not get much more than a foot high and wide. Some may stay half as tall. Their lower leaves can get three inches long, with crenate margins. Minute yellow, orange, red, pink or creamy white flowers bloom for late autumn or winter. Garden plants require shelter from chill through winter and hot sunlight through summer. Most are houseplants that appreciate copious sunlight.
The fifty or so specie of yucca that are native to North and Central America are horticultural nonconformists. Like most of the related agaves and aloes, they are classified as succulents; but none have succulents leaves. Their stems store moisture, but are about as succulent as trunks of palm trees. Actually, many are classified as trees because they develop heavy and sculpturally branched trunks, but they are really just big herbaceous perennials that get very old.
From the Big Bend region of Texas and adjoining Mexico, beaked yucca, Yucca rostrata, happens to be one of the yuccas that develops a trunk, but grows so slowly with such billowy foliage, that it respected more as a striking foliage plant. The largest and oldest plants get no larger than fifteen feet tall and rarely develop one or very few branches. Most are less than ten feet tall with single but bulky symmetrical foliar rosettes. The individual grayish leaves are limber and narrow, but very abundant. ‘Sapphire Skies’ has even more striking bluish foliage.
As if the excellent foliage were not enough, mature beaked yucca blooms with small white flowers on big spikes nearly two and a half feet tall. Spikes can appear through winter and are typically finished blooming by spring, before summer dormancy, but do not seem to be too devoted to any particular schedule.
Beaked yucca is less common than it should be; perhaps because it is difficult to grow in nurseries. Besides, they are not for every garden, and are very likely to rot where they get watered as frequently as most other plants get watered. They do not mind if watered perhaps a few times through summer, but are more than satisfied with what they get from rainfall.
Mandarin orange, Citrus reticulata, and nuts are some of the more traditional goodies for Christmas stockings. In Northern Europe centuries ago, nuts from the Americas were still exotic treats. The availability of perishable citrus fruits from Mediterranean regions relied on expensively efficient shipping. Consequently, citrus fruits were almost like delicacies.
Even when shipping was slow, Mandarin oranges ripened in time to arrive by Christmas. However, they needed fast shipping because they are more perishable than other citrus. They are innately more prone to oxidation because their rind and segments fit so loosely together. Of course, that is why they are so delightfully easy to peel, pull apart and share.
Mandarin oranges are smaller, more oblate, brighter orange, but also more variable than common sweet oranges. Among their many cultivars, their smaller leaves and thorniness are likewise variable. Very few very old trees grow taller than fifteen feet. Tangerines are merely barely genetically distinct Mandarin oranges that developed within the Americas.
Prickly thickets of California wild rose, Rosa californica, are not often much to look at, even while adorned with small and sparse pink roses in spring and summer. The fragrant flowers can actually range in color from white to rich pink, and may have more petals, but are not abundant enough to be very impressive at any one time. In autumn though, all the flowers that bloomed in the previous few months leave bright orange or red fruiting structures known as ‘hips’, that linger on the bare canes through winter.
The rose hips of California wild roses had historically been used to make herbal tea because they contain so much vitamin C and have a pleasant flavor. (California wild rose is a ‘tea’ rose but not a hybrid ‘T’ rose.) They can also be made into jelly or sauce. The only problem is that birds like them too, so often take them before anyone else has a chance to.
The most common of a few species of cottonwood that are native to California seems as if it should not be. Populus deltoides is the Eastern cottonwood. This name implies that it should be native primarily to regions of the East. Yet, it naturally inhabits every American State except for Hawaii and Alaska. Since it is so familiar locally, it is simply cottonwood.
It grows wild in riparian ecosystems, and occasionally sneaks into adjacent landscapes. It is almost never an intentional acquisition. Cottonwood grows too aggressively and too large for refined home gardens. It works better as a grand shade tree for parks and urban waterway trails. As a riparian species, it requires either riparian ecosystems or irrigation.
Mature cottonwood trees may be almost a hundred feet tall, and rather broad if exposed. Their bark is handsomely furrowed. Yellow autumn color of the deciduous foliage can be surprisingly vibrant within arid climates, or if rain is later than frost. Vigorous trees can be susceptible to spontaneous limb failure, so may occasionally justify aggressive pruning. Roots might be voracious.
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.
Cherry, Prunus avium, is one of the more popular fruits of summer. However, winter is the season for planting new trees and pruning mature trees. Pruning is comparable to that of other stone fruits, but to a lesser degree. Their sweet fruits are typically less than an inch and a half wide, so are relatively lightweight. Docile trees may not need annual pruning.
Home garden trees with dwarfing rootstocks should grow no taller than about fifteen feet. Some stay less than ten feet tall. Orchard trees with standard rootstock grow significantly taller. Wild or feral trees can grow forty feet tall, with their fruit beyond reach. Old cultivars mostly require another compatible cultivar for pollination. Some modern cultivars do not.
Cherry fruits are mostly rich deep red, but can be dark blackish red or pale orangish pink. Early spring bloom is brief but profuse and splendidly clear white. Three to four inch long leaves that are deep green through summer become bright yellow or golden yellow prior to defoliation during autumn. Even the silvery young bark of some cultivars is appealing.