Ed Brennan, Benicia's star Consulting Arborist and Bicycle Designer, led our first Bicycle Tree Tour on November 13, 2010.
Photos of the tour are available by clicking here.
A google map features our stops along the tour:
The first tour featured the following trees:
California pepper (Schinus molle) is native to Peru. It is associated with the gardens of the Spanish Missions in California. Its trunk gets gnarled with age, and is often hollow. It is a very fast growing tree, and the wood is soft and decays easily. Surface roots can be invasive and damage sidewalks. It has a pest, the pepper tree psyllid (Calophya shini), but it is largely under biological control.
California bay (Umbellularia californica): native to California. Its leaves can be used as a flavoring agent in food, although another tree is used for this purpose commercially, the Grecian laurel (Laurus nobilis). The causal agent of “sudden oak death”, Phytophthora ramorum, uses bay leaves as a site to complete its life cycle. California bay is suitable for residential landscapes where there is room for a large stature tree.
Incense cedar (Calocedrus decurrens) is native to the mountainous regions of Oregon, California, and Baja. It is more adaptable to low elevation climates than most trees from the mountains. It can be quite symmetrical, although not especially wind tolerant. Notable for the flat nature of its foliage, and can be fragrant in warm weather.
European white birch (Betula pendula) is native to Europe and Asia Minor. Often planted in groups of 3 in turf grass, the quintessential suburban landscape. Not tolerant of drought, it has recently become the host of the bronze birch borer. It is also a prime host of aphids.
Monterey pine (Pinus radiata) is native to several coastal sites in California and Mexico. It is a fast growing tree and was popular to plant during building booms in the 50’s and 60’s. Because it is adapted to the climate of the fog belt, it does not fare well in the inland regions. It has so many pests and diseases they are too numerous to mention. If pines appeal to you, consider a Canary Island pine, which we will be seeing later.
Canary Island date palm (Phoenix canariensis): native to the Canary Islands, in the Atlantic Ocean off the coast of Africa. They tolerate a wide variety of climatic conditions and are increasingly popular, especially in commercial landscapes. There are many in the older areas of Benicia, so many that you might think of it as Benicia’s signature tree. They sprout prolifically from seed, which may explain their large numbers here. They are tolerant of transplanting, and serve as habitat for many forms of wildlife.
Japanese maple (Acer palmatum) is native to Japan and Korea. There are many varieties and is one of the most highly cultivated trees commercially available. Placement is important because they can be damaged by constant wind and full sun.
Japanese snowbell (Styrax japonica) is a small to medium size tree prized for its white flowers, contrasting with dark green foliage. The flowers are fragrant when temperatures are warm enough.
Sandalwood (Myoporum laetum) is native to Austrailia and New Zealand, and is used as a barrier planting, median strip planting, etc. Notice the pest damage to the new growth, caused by the Myoporum thrips (Kambothrips myopori). The pest has only recently found its host in California.
Sweetgum (Liquidambar styraciflua) is native to the eastern U.S. It is prized for its fall color. Ideally a pyramidal shape, which it often loses when pruned. It has an aggressive surface root system that is good at lifting sidewalks and driveways. Spiny fruits can be a problem when they drop on paved surfaces.
English hawthorn (Cretaegus laevigata) is native to Europe and North Africa. This is a small to medium size tree that can get as tall as 25’. It has thorns, as the name suggests, and is susceptible to leaf spot causing fungi. A relative, the Washington thorn (C. phaenopyrum) is a more attractive tree with softer foliage that has good fall color.
Coast live oak (Quercus agrifolia)
This evergreen oak is native to California. It grows to a height of 75', with a similar crown spread. More tolerant of human impacts than other native oak species, it has done well since European settlement. Popular in residential landscapes where room allows, as well as park settings. Common pests include the California oak moth, a bark beetle, oak root fungus, and several foliar diseases. Note the overhead wires.
Catalina cherry (Prunus lyonii) is a shrubby tree, native to the Channel Islands. Foliage is dense and dark green. It produces a small inedible fruit that can be a problem when it drops on paved surfaces or patios. Something to consider for those interested in native vegetation.
Olive (Olea europaea) is native to Europe and was introduced by the Spanish missionaries. It can be a handsome medium size tree with an unusual color, similar to sage. When mature, their trunks become quite gnarled and look ancient. Fruit can be a problem when planted in proximity to walkways or other paved surfaces. Fruitless varieties are available.
Japanese loquat (Eriobotrya japonica) is a nice looking medium size tree. It produces fruit when temperatures are warm enough. The fruit is not popular for eating, and can be a problem with staining pavement and attracting rodents. A close relative, the bronze loquat (E. diflexa), is often used as a street tree in urban areas.
Deodar cedar (Cedrus deodara)
Native to India, Pakistan, and parts of Afghanistan. It has a rich cultural history, is the national tree of Pakistan and is worshiped by some Hindus. Grows well in Northern California. It is a large tree at 60 feet tall. The color varies from green to bluish. Branches are generally level with the tips drooping. No serious pests or diseases. Note stability issues. Note juvenile and mature forms.
Fruit tree landscape, a good use of trees instead of turf grass makes for an attractive and useful yard.
California fan palm (Washingtonia filifera) is the only palm native to California. It grows in desert oases in southern California. Palm Springs is named for them, and there is a state park at Palm Canyon with a large native stand. Not suitable for planting in a cool, damp environment such as Benicia. Adapted to a drier climate, they are susceptible to fungus diseases here.
Italian cypress (Cupressus sempervirens) is native to southern Europe. They thrive in hot, dry climates such as Sonoma County. They seem to tolerate the dampness and cool temperatures of Benicia and there are many examples. They get large but do not take up a lot of room because of their columnar shape. Susceptible to several diseases, usually when subjected to drought stress or excessive moisture.
Canary Island pine (Pinus canariensis): native to the Canary Islands, off the west coast of Spain in the Atlantic Ocean. A large, but not huge, growing tree with rough reddish bark and pendulous needles. It is often planted as a replacement for Monterey pine, and is resistant to most of the many pests and diseases that plague that species. It is one of very few conifers that can produce foliage from woody tissue when needed, coast redwood being another.
Coast redwood (Sequoia sempervirens): native to the west coast of California and widely planted in landscapes. Fast growing and a large tree in maturity, the tallest tree on earth. When planted away from the coastal fog belt it is dependent on irrigation. It has some minor foliar pests and is a host of oak root fungus. It is not tolerant of wind and becomes misshapen when exposed to constant breezes. Although it is widely used in residential landscapes, its fast growth rate and large size often pose problems.
Fremont cottonwood (Populus fremontii) is native to the arid areas of the western U.S, and named for the early explorer John C. Fremont. It is a large growing tree and is notable for its aggressive surface root system. Not suitable to plant in residential landscapes, or even parks. The wood is soft and brittle, and large roots develop at the surface making turf maintenance problematic.
Flax-leaf paperbark (Melaleuca linarifolia) is native to Australia and is noted for its tolerance of poor planting sites. It is prized for its umbrella shape and stunning display of cream-colored flowers. The Benicia State Recreation Area has many of these. A close relative, the cajeput tree (Melaleuca quinquinervia), is also commonly planted. There is one in this park.
Giant sequoia (Sequoiadendron giganteum)
Native to the western slopes of the Sierra Nevada, this is the world's largest tree by volume. It grows to 280' in height, and up to 24’ in diameter. They do not do well long term at lower elevations, where they are a host of Botryosphaeria disease.
Austrailian willow (Geijera parvifolia) is native to Austrailia, of course. It has a weeping growth habit and long, slender leaves the shape and color of green beans. They are difficult to prune because of their shape and diffuse branch structure. Pruning the bottom of the crown for clearance beneath is usually required.
Chinese pistache (Pistacia chinensis) is a small to medium sized tree prized for its fall color. Mature trees develop a round crown and dense foliage, although it takes a few years for this to develop. No important pests or diseases. It is widely used in streetscapes and residential landscapes.
Italian stone pine (Pinus pinea) is native to southern Europe. It develops massive low branches that are often weakly attached. This results in limb failures in many cases. In Italy the low branches are removed in the nursery, reducing the severity of the problem. They get quite large and are often planted in inappropriately small spaces.
Maidenhair tree (Ginkgo biloba) is native to China and became popular one to two decades ago. They are a slow growing but well behaved tree prized for their fall color. Purchase these from a reliable source, as only male trees should be planted. Females produce fruit which has a noxious odor.
Arizona ash (Fraxinus velutina) is native to Arizona and was a popular street tree in past decades because of its tolerance of marginal growing conditions. These are widely planted in Benicia apparently as the result of a planting program. Many are in poor condition and infested with mistletoe. As they decline, what will we replace them with?
London plane (platanus X acerifolia) is a hybrid of two other sycamore species. They are associated with the church graveyards in London, where they were planted to cleanse the air during the bubonic plague. They are used in formal gardens, where they are pollarded, and as street trees. Although they have serious pest and disease problems, they are a tough tree able to adapt to urban settings. They rarely cause sidewalk damage.
Tree of heaven (Ailanthus altissima) is an ill-mannered but fast growing tree. Native to China, its roots spread rapidly and send up shoots, establishing new trees quickly. It should not be used in residential landscapes.
Scarlet oak (Quercus coccinea) is native to the eastern U.S. It is a large tree, reaching 60’. It is a good tree for residential use where space permits, since it is tolerant of summer irrigation unlike native vegetation.