SelecTree: Tree Characteristics GlossaryA - B - C - D - E - F - G - H - I - L - N - P - R - S - T - U - W
These trees include those with thorns, spines or other sharp plant parts. This feature is not always a disadvantage since these trees can intentionally be planted as a barrier.
Bark Color is not often recognized as an added feature of the tree, but color variation on twigs and trunk is as extensive as that of leaves. Bark color may be very variable as the tree matures, and can be an interesting winter feature. It can also beautifully contrast or compliment foliage during the growing season. The mature color is what is identified here, as observed on the trunk of the tree. Some trees have multicolored bark, and are identified as 'multicolored', as well as with the other color selections. 'Striking' has been included as an option if the tree's bark is unusually good looking. Select a color term which comes closest to the one you desire, if it is not already listed.
Bark Texture of a tree may vary depending upon the age of the tree and the location on the tree where the bark is observed. In SelecTree, it is associated with mature trees, observed on the trunk of the tree. Bark Texture is reported as follows:
- Having sections which project in distinctive block-like shapes (pear, flowering dogwood).
- Tending to peel away in layers, and eventually fall to the ground (paperbark maple, common horsechestnut).
- Having loose thread-like fibers (bottlebrush, date palm).
- Having grooves, cracks, splits or narrow depressions, opposite of 'ridged' (noble fir, white fir, Italian cypress, Japanese maple).
- Having raised lines or ridges, opposite of 'furrowed'.
- Having a bumpy, uneven surface, not necessarily following any pattern or structure (Norfolk Island pine, lily magnolia).
- Part or wholly covered with scales or thin plates (Chinese elm, sycamore).
- Having an even consistency, without irregularities or projections (red alder, lemon).
- Covered with spines, thorns or other stiff projections (sawleaf zelkova, floss silk tree).
- Marked with shallow stripes (weeping bottlebrush, sour cherry).
(WARNING! Only 234 trees have this information. Using this category in an attribute search will limit matching trees considerably.)
Biogenic Emissions estimates volatile organic compound (VOC) emissions from vegetation and is an important consideration when large-scale tree plantings occur. This is especially important if air quality in the area is already poor. The information contained in SelecTree is taken directly (with permission) from the paper Low-Emitting Urban Forests: A Taxonomic Methodology for Assigning Isoprene and Monoterpene Emission Rates, by Michael T. Benjamin, Mark Sudol, Laura Bloch and Arthur M. Winer. Atmospheric Environment. Vol.30, No.9, pp.1437-1452, 1996.
Trees are classified as 'Low', 'Moderate', or 'High', based on "the sum of the hourly emission rates of isoprene and monoterpenes, expressed as microgram emissions per gram dry leaf weight per hour", as follows:
- Less than 1 microgram total emissions
- Between 1-10 microgram total emissions
- Greater than 10 microgram total emissions
Branch Strength is controlled by the inherent strength of the wood, although strong winds, branching patterns, pruning practices, and overly abundant fruit can cause broken branches. Limb breakage can be a common occurrence in trees, but some are more prone to it than others. Trees with weak wood include those that have been commonly reported for limb breakage and disrupting power in the PG&E service area (central to northern California).
SelecTree's invasive plant information is taken from Cal-IPC California Invasive Plant Council on August 2006 and is displayed in the tree notes or memo section of the tree report.
Cal-IPC rates invasive plants as High, Moderate and Limited.
- Species have severe ecological impacts on physical processes, plant and animal communities, and vegetation structure.
- Species have substantial and apparent but generally not severe ecological impacts on physical processes, plant and animal communities, and vegetation structure.
- Species are invasive but their ecological impacts are minor on a statewide level or there was not enough information to justify a higher score.
'Yes' means the tree is edible or especially preferred by deer, 'No' means the tree is neither edible nor appealing to deer.
Density in Leaf is important in determining the amount of shade and shelter a tree may provide. Factors to consider are a tree's leaf size and shape, and branching pattern.
Density Out of Leaf is important for those interested in visual screening or shelter during the winter. This category refers to the density of the natural branching pattern.
Desirable Wildlife Plant
Every tree could be construed to have wildlife value, but those listed here are especially useful because they provide an easy food or shelter source.
Disease Resistance is a genetic characteristic that determines the tree's ability to resist disease. Trees that are resistant to a disease either do not contract the disease or show little or few symptoms of the disease. Possessing low-level disease symptoms does not significantly affect the health of the tree nor its aesthetic qualities. Because not all trees have been tested for all diseases, much data is not known or documented. This field makes no claim of listing all diseases, or their complex types to which tree show a degree of resistance. Also examine the 'Disease Susceptibility' field for more information on diseases.
Trees are susceptible to diseases. A disease can result from bacteria, fungi or viruses. Sometimes even the environment contributes to diseases: air pollution, mechanical damage, a deficiency or excess of nutrients, water, sunlight, or the wrong climate. Generally for a disease to occur, three conditions must exist. The host must be present; the pathogen must be present; and the environmental conditions conducive to the disease must be present. Because not all trees have been tested for all diseases, much data is not known or documented. This field makes no claim of listing all diseases, or their complex types of any particular tree. Also examine the 'Disease Resistant' field for more information on diseases.
Exposure is reported as follows:
- 6 or more hours of direct sunlight per day
- Less than 2 hours of direct sunlight per day
- 2 to 6 hours of filtered sunlight per day
Live in a fire risk area? Please check with your local Fire Council or Fire Department before planting trees!
(WARNING! Only 305 trees have this information. Using this category in an attribute search will limit matching trees considerably.) Fire Resistance information is taken from The UC Forest Products Laboratory, Vegetation Guide for Landscaping in High Fire Risk Areas, 1997. Current information on this resource is available at UC Forest Products Laboratory - PreFire Engineering.
Favorable fire performance rating is based on the following characteristics:
- a low surface area to volume ratio, such as plants with thick, broad leaves as opposed to those with narrow, needle-like leaves.
- a high moisture content, as found in succulents and other plants with fleshy foliage.
- a low percentage of dead matter or debris.
Unfavorable fire performance rating is based on the following characteristics:
- a high surface area to volume ratio.
- a low moisture content.
- a high percentage of dead matter or debris.
Conflicting fire performance rating is based on being listed as fire resistant in some references and as fire prone in other references.
Note: All trees are flammable under certain conditions. Care should be taken to lessen factors that contribute to their flammability and hazard. For further information on tree selection precautions, visit the Right Tree Right Place information.
Flower Color attempts to select the predominant color appearance of the flowers, but not the slight variations which occasionally occur. Typically, the colors are on petals, but occasionally the stamens are the more visible color elements. As with color of foliage and fruit, flower color can help the homeowner assess the tree's ornamental value. Select a color term which comes closest to the one you desire, if it is not already listed.
- separate male and female flowers on the same tree.
- either male or female flowers. Trees may be referred to as male or female.
- male and female parts in each flower.
Flower Showiness attempts to describe the value of the flower as a key aesthetic characteristic. 'Showy' flowers are those which are large or colorful enough to stand out prominantly, while 'inconspicuous' flowers are aften difficult to see or identify. Some genera, such as Cornus and Cotinus, are described here as having 'Showy' flowers when in actuality the flowers are very inconspicuous next to showy bracts or inflorescences.
Trees produce flowers at different times throughout the year, depending on the species. This field identifies which season the flowers will appear on the tree when growing in central and northern California (PG&E's service area). Other variables, such as weather or watering schedules, can also influence flowering time.
refers to the distinct foliage color that occurs on the upper side of the mature fall leaf. Fall foliage is often an aesthetic consideration when choosing a landscape tree because of the seasonal value and beauty it can add to an area. Weather, soil type, and cultural practices can influence reliability and intensity of fall foliage color in some trees. Select a color term which comes closest to the one you desire, if it is not already listed.
Foliage Growth Color refers to the prominent foliage color that occurs on the upper side of the fully expanded leaf. Weather, soil type, and cultural practices can influence the foliage growth color in some trees. Select a color term which comes closest to the one you desire, if it is not already listed.
Foliage Shape is varied and complex. Foliage Shape is defined as follows:
- Bipinnately Compound
- opposite leaflets (like pinnately compound leaves) that are subdivided themselves into leaflets.
- having a heart-shaped outline.
- having a triangular outline.
- having the outline of an ellipse (longer than broad with blunt or round ends).
- curved and tapering to a point, sickle shaped.
- large compound or simple leaves typical of palms or ferns.
- ovate leaves with a spinose margin.
- four to six times as long as wide, narrow and tapering at each end.
- narrow and elongated with nearly parallel sides.
- a leaf having deeply indented margins.
- stiff, narrow leaves typical of conifers.
- broader and rounded at the tip, and tapering at the base.
- three to four times longer than wide, with approximate parallel sides.
- egg shape in outline, with the narrow end attached to the stem.
- broad, ellipse shape with rounded ends.
- broad and rounded at the base and tapering at the end, egg shaped.
- having lobes radiating from one point.
- Palmately Compound
- a leaf composed of leaflets which radiate from one central point.
- Pinnately Compound Odd
- leaflets arranged symmetrically on either side of a central petiole with a single terminal leaflet at the end (i.e. resulting in an odd number of leaflets).
- Pinnately Compound Even
- leaflets arranged symmetrically on either side of a central petiole with a pair of leaflets at the end (i.e. resulting in an even number of leaflets).
- a simple leaf having narrow lobes or divisions not reaching the midrib.
- resembling a rectangle in outline.
- resembling a rhomboid in outline, diamond shaped.
- having a circular outline.
- consisting of overlapping layers, like fish scales.
- shaped like a spatula or spoon in outline, broad rounded apex and narrow base.
- having three leaflets attached to a central point.
- a simple leaf with three lobes.
Foliage Type refers to whether a tree retains or drops its foliage when they are no longer needed for energy production. Foliage Type is defined as follows:
- trees lose their leaves completely every winter.
- trees never lose all of their leaves/needles at one time, but generally have specific periods of leaf drop. They remain green throughout the winter.
- Partial Deciduous
- trees will lose a majority of their leaves during fall, but will retain a lower density of leaves during dormancy.
Fragrance can act as an asset or a disadvantage. Some people are allergic to pollen which they associate with flower fragrance. However, some flowers may be fragrant but not allergenic. Other individuals may decidedly want pleasant smelling plants and enjoy the wildlife they attract. Fragrance can derive from all parts of the tree, flowers being the most typically fragrant. Some trees are not actually fragrant until their bark, leaves or roots are crushed. Only those plant parts which emit their fragrance freely into the air, and would therefor be a direct influence on a homeowner's property, are listed here. Some trees have unpleasant smelling pollen, and these foul or unpleasant odors are also noted.
Fruit Color attempts to select the predominant color appearance of the fruit on the tree when viewed from a distance, but not the slight variations which occasionally occur. As with fruit size, relative quantity and color of foliage, fruit color can help the homeowner assess the fruit's ornamental value. Select a color term which comes closest to the one you desire, if it is not already listed.
Fruit Size is the size (in inches) to which the mature fruit may potentially develop. Many variables influence the actual mature size of the fruit, and any one kind of fruit can develop into a wide range of sizes. The "Very Large" size class is very variable since some fruits may mature to eight inches or more in size. Fruit size may help to determine the possible amount of work to pick or clean up the fruit. Fruit Size is defined as follows:
- Very Small
- less than 0.25 inches
- 0.25 to 0.50 inches
- 0.50 to 1.50 inches
- 1.50 to 3.00 inches
- Very Large
- greater than 3.00 inches
Fruit Type is reported as follows:
- a small, dry, thin-walled fruit that does not split open when ripe.
- a nut partially surrounded by a fibrous or woddy cap (involucre) (oak).
- an outer covering or appendage surrounding the seed, arising at or near the point at which it is attached to the branch (yew).
- aggregate fleshy fruit having few or many seeds, but not a single stone (mulberry).
- fruit that contains two or more seeds, and that dries and splits open not necessarily along any existing ridge or seam.
- a conical structure consisting of stiff, overlapping, woody scales between which are the seeds (pines, hemlock).
- fleshy fruit having a single hard stone (cherry, olive, peach).
- a single chambered fruit that splits along only one seam to release its seeds (catalpa).
- a form of berry having a thickened, leathery rind and juicy pulp divided into sections (orange).
- having a membranous or green outer envelope (walnut).
- like a nut, but being a dry, single seeded fruit, which doesn't shed its seed when ripe. The term is often used loosely of any hard fruit.
- a fruit that contains many seeds, and that usually dries and splits open at the seam of its pod-like protective coating (honey locust).
- fleshy fruit having seeds, but no stone (apple, pear).
- Winged seed/Samara
- having wing-like structures on the exterior of the seed by which the air might lift the seed for dispersal (maples).
Fruit Value is reported as follows:
- the fruit is safe to eat, but the preparation requirements should be researched, since not all fruit can be eaten fresh.
- Wildlife Value
- this is a benefit to those who wish to attract or maintain animals in their area. These trees should not be planted if you do not want to attract wildlife.
Fruiting Habit is the fruiting characteristic displayed by trees that may be desired or undesired. Fruiting Habit is defined as follows:
- no fruit is produced, or the fruit aborts before it matures. Some tree varieties have been specially developed to not produce fruit.
- a small quantity of fruit is produced.
- a great abundance of fruit is produced that may be very showy or edible. This may be desired if you are interested in harvesting the fruit for eating, but may be undesired and considered messy if not.
- fruit is retained or appears on the tree most of the year.
Fruit can appear any time of year on trees depending on the species. Other variables, such as weather or watering schedules, can also influence fruiting time.
Functional Form refers to how the can be used in the landscape based on its characteristic form. Functional form is defined as follows:
- Low Canopy
- forming an overhead canopy of tree branches at a height of 20-35 feet.
- High Canopy
- forming a canopy at a height of 35-50 feet.
- Extensive area
- trees requiring large spaces to avoid unnecessary liabilities in terms of costly maintenance and creating potential hazards in the future, including damage to homes and utility services or injuries to people.
Growth Rate (in inches) identifies the maximum relative rate a tree will grow. As with height, urban environments will provide many influencing variables.
Maximum Growth Rate is defined as follows:
- Slow (12)
- 1 to 12 inches per year
- Slow to Moderate (12-24)
- 12 to 24 inches per year
- Moderate (24)
- 24 inches per year
- Moderate to Fast (24-36)
- 24 to 36 inches per year
- Fast (36)
- 36 inches or more per year
Habit refers to the tree's natural growth habit. Habit is reported as follows:
- generously sending branches out to the sides and taking up available space. This term is often used as both a form and a growth habit description, generally describing trees which are wider that they are high.
- tending to grow tightly and close together within itself.
- distinct upward growth, vertical configuration.
- long, narrow branches which tend to droop downward.
Some plants produce substances or allergenic materials which can harm humans or animals who come in contact with them. The level of toxicity is variable in the 'poisonous' selection. In many cases the toxicity level may be similar to that of many common plants such as the green portion of carrots, the seed of nutmeg, or the seeds of an apple. Consult your local or county Public Health Services or Agency for further information on plant toxins and irritants. These are reported as follows:
- the tree may cause an allergic reaction due to its airborne pollen or a chemical it extrudes onto its bark or leaves.
- some aspects of the tree such as plant hairs, oils or odor may cause irritation to the skin, eyes, nose or throat.
- a substance produced by the tree can cause injury, illness or death.
Height is the maximum height (in feet) to which a tree may potentially grow. Many variables influence the actual final height of a tree. References sometimes vary considerably when reporting maximum tree height. In this case, SelecTree will report a range of potential maximum heights. Urban environments may inhibit the potential of a tree to reach the maximum height it would in a natural setting. It is important, though, to consider overhead restrictions before planting a tree.
Height is defined as follows:
- Very Small (20)
- 10 to 20 feet
- Small (25)
- 20 to 25 feet
- Small Medium (35)
- 25 to 35 feet
- Medium (50)
- 35 to 50 feet
- Large (65)
- 50 to 65 feet
- Very Large (> 65)
- over 65 feet
SelecTree's invasive plant information is taken from Cal-IPC California Invasive Plant Council and is displayed in the tree notes or memo section of the tree report. Additional information is available at invasive plants.
Cal-IPC rates invasive plants as High, Moderate and Limited.
- species have severe ecological impacts on physical processes, plant and animal communities, and vegetation structure.
- species have substantial and apparent but generally not severe ecological impacts on physical processes, plant and animal communities, and vegetation structure.
- species are invasive but their ecological impacts are minor on a statewide level or there was not enough information to justify a higher score.
Landscape Application refers to how the tree's natural characteristics and form can be used in the landscape. Landscape Application is reported as follows:
- tree can be used to create a visual of physical barrier 10-35 feet high.
- tree grows in riparian areas and can be used to restore or reestablish such areas.
- Buffer Strip/Median
- a tree suited for a median strip in a highway or a buffer strip around the edge of a parking lot. Most local governments regulate planting in these areas.
- a tree (such as River Birch) that is worthy for planting by itself and featured in the landscape due to one or several attractive traits such as glossy or unusual foliage, striking habit, nice bark, interesting multiple-trunked arrangement, attractive, long-lasting fruit or flower display.
- usually a small tree. Trees in containers need regular irrigation and fertilization and require frequent replacement.
- Street Tree
- recommended for planting along a street where there is plenty of soil space for root expansion.
- Shade Tree
- A tree (such as Live Oak) with a rounded, oval or spreading habit that usually casts significant shade.
Common Landscape Use refers to the tree's artificially encouraged form. Landscape Use is reported as follows:
- intensive, long-term pruning to create decorative shapes, such as animals.
- carefully trained, dwarfed plants designed to look like a tree or landscape in miniature. Created by wiring and pruning of branches, and pruning of roots.
- branches can be trained to some formal shape or pattern on a flat plane against a wall, or on a trellis or fence.
- can be clipped to form a solid screen or barrier.
- branches are woven together to form a 'mat', useful as a hedge or arbor.
- a tree whose major branches are cut to short branch stubs, where shoots are annually pruned off completely to maintain a low growth form each season.
Fruits, flowers, leaves, twigs and bark can be considered litter if they tend to fall with frequency, long duration and abundance. These plant droppings create maintenance hassles when the trees are located over drives, walkways, patios or planting areas which are meant to be kept relatively clean. Problems can include hazardous slippery or bumpy surfaces, staining of surfaces, and smothering of small plants to the point of preventing their growth. However, except for fruits that are sizable and/or wet, most litter is tolerable. Some litter may be left as mulch and contribute to the improvement of the soil. If the tree drops excessive amounts of any of the mentioned plant parts, it is noted here. The fruit type, wet or dry, is also identified.
Longevity is an important consideration for long-term shading, screening, beauty and value of a property. Short-lived trees may also be wonderful shade trees, and can be useful where permanence is not the ultimate goal. Longevity may vary depending on proper selection of adapted species, care the tree receives, risk of mechanical damage, and the presence or lack of diseases and pests. Longevity is reported as follows:
- Very Short
- less than 50 years
- Moderately Short
- 40 to 60 years
- 50 to 150 years
- Moderately Long
- 100 to 175 years
- Very Long
- greater than 150 years
Botanical names (Family, Genus and Species) are the Latin nomenclature for a plant by which it is identified. Using botanical names ensures the acquisition of the exact plant desired, because common names of plants are not consistent from place to place. The botanical name consists of three parts, family, genus and the species. Family and genus are always first (respectively), with the first letter capitalized. The species name comes next, and is usually in lower case. Helpful references are listed here.
- The Plant List
- Jepson Interchange Parallel Treamtment to TJM2 (Use for all California natives)
Cultivars are horticulturally or agriculturally derived varieties of a plant, and they are usually cultivated for specific characteristics such as color, lack of or production of fruit, or unique foliage characteristics.
Common names of plants vary tremendously from place to place, and are not a reliable identifying feature. Common names are usually of local value, because they derive from laymen gardners who create names based on some visible characteristic, or reference to a local individual.
Pest Resistance is a benefit to those who desire a tree for an environment known to host a particular pest. Because not all trees have been tested for all pests, much data is not known or documented. This field makes no claim of listing all pests to which tree show a degree of resistance. Also examine the 'Pest Susceptibility' field for more information on pests.
Different plants attract different pests, and some pests will require special and regular treatments to prevent damage to the tree or its fruit. Because not all trees have been tested for all pests, much data is not known or documented. This field makes no claim of listing all pests of any particular tree. Also examine the 'Pest Resistant' field for more information on pests.
Root Damage Potential
Root Damage Potential attempts to qualify the tendency trees have of causing damage with their roots. Root damage is usually caused when tree roots remain close to the surface of the soil. Tree roots can cause costly damage to paving, structures and even underground utilities. Because roots nearer the tree trunk will enlarge earlier and grow more rapidly, care should be taken to space trees appropriately from structures. Local environmental and tree care conditions, such as soil type or watering habits, can affect a tree's root development. Long, deep waterings can encourage downward root growth. Shallow soils will force roots to grow horizontally rather than vertically.
The terms 'Low', 'Moderate' and 'High' are used in this category. Avoid planting trees with high root damage potential near structures.
Salinity Tolerance ratings reflect soil salinity in two geographic areas (coastal or inland). The terms 'Good' and 'Moderate' are used to qualify each of the ratings in this category. Trees that do well in saline conditions qualify as 'Good', while trees that don't do as well qualify as 'Moderate'.
Salt Spray Tolerance
Salt Spray Tolerance ratings, designated as 'Low' 'Moderate' and 'High', are available only for some trees and are reported as follows:
- Tolerant of direct exposure to the ocean front.
- Tolerant of moderate exposure to salt spray.
- Tolerant to some exposure to salt spray well back from the dunes.
Seaside Tolerance ratings reflect the different degrees of protection from the coastal elements. All trees mentioned in this category are within Sunset Zones 17 or 24 in California. Those not in either of these zones are not suited for seaside growth.
The terms 'Good' and 'Medium' are used to qualify each of the ratings in this category. Trees that do well in a zone qualify as 'Good', while trees that don't do as well qualify as 'Medium'.
- Harsh Zone
- The area directly adjacent to the coast which receives high salt spray, harsh winds, and blasting sands is an extreme seaside condition and we do not recommend any trees for this area. If you desire to plant trees in this area experiment with trees rated 'Good in Moderate Zone'. An example of a harsh zone is Pacifica.
- Moderate Zone
- Within this harsh area there are sheltered locations which receive less seaside impacts. These are termed 'Moderate Zones'. An example of a moderate zone is the greater part of San Francisco.
- Mild Zone
- Areas further inland are considered 'Mild Zones'. An example of a mild zone is Berkeley.
- The south coast
- is generally warmer and milder than the north coast. This is referred to as the 'South Coast'. SelecTree categorizes trees suited for these milder areas.
Soil Moisture is reported as follows:
- Naturally wet areas (high rainfall)
- Damp soil most of the year (moderate rainfall)
- Crumbly or compacted soil (little or no rainfall)
Soil Texture is reported as follows:
- hard, fine to small flattened particles, slow to drain. If you rub clay soil when wet, it will be sticky and smear easily. When dry, it forms clods.
- good mixture of clay/silt/sand particles, organic matter and moisture. Generally the best kind of soil in which to grow garden plants.
- large rounded particles, fast draining, few nutrients, quick to dry. Its gritty texture is easy to feel on your fingers. Many drought tolerant plants and California natives are suited to this soil type.
Soil pH is how acid or basic a soil is. Another term for basic (in this context) is alkaline. The terms used in SelecTree are defined as follows:
- Very Acidic
- 5.3 to 6.0
- Slightly Acidic
- 6.1 to 6.9
- Slightly Alkaline
- 7.1 to 7.5
- Very Alkaline
- 7.6 to 8.2
Sunset's Garden Climate Zones
Sunset's Garden Climate Zone system is based on a combination of six factors. They are:
- Influence of the Pacific Ocean
- Influence of the continental air mass
- Mountains and hills
- Local terrain
Although there are 24 climate zones represented in the west, California does not have zones 5,6,or 12. Note: SelecTree doesn't provide for the zone subdivisions (a and b).
Tree Shape identifies the generally definable shape tree canopies take as they mature. As with height, care and urban environments will provide many influencing variables. Tree shapes are defined as follows:
- erect and almost parallel, resembling a column.
- oval at the base, elongated and tapering to a narrower width at the top.
- Fan Palm
- fan shaped leaves with venation of the leaves extending like the ribs of a fan.
- Feather Palm
- palm frond resembling a feather with leaflets growing outward from a long central stem.
- appearing elliptical, resembling an egg.
- ball-like or circular.
- Sword Palm
- palm fronds which are undivided and upright, bladelike.
- branches extending outward and down, as an umbrella does.
- a narrow base, widening and arching outward towards the top.
USDA Hardiness Zones
USDA Hardiness Zones 4 - 11 are found in California. A zone is an area based on the average annual minimum winter temperature, divided into 10-degree °F zones. Zone designations help determine which plants are most likely to thrive at a given location. SelecTree does not include the further differentiated sub-zones (a, b).
- Zone 1
- below -50 °F
- Zone 2
- -50 to -40 °F
- Zone 3
- -40 to -30 °F
- Zone 4
- -30 to -20 °F
- Zone 5
- -20 to -10 °F
- Zone 6
- -10 to 0 °F
- Zone 7
- 0 to 10 °F
- Zone 8
- 10 to 20 °F
- Zone 9
- 20 to 30 °F
- Zone 10
- 30 to 40 °F
- Zone 11
- above 40 °F
Utility Friendly Trees
Trees labeled with this icon are safe for planting near residential power lines. For further information see Utility Precautions.
Attracts Wildlife indicaates the tree has qualities which encourage the noted animal to feed (birds, bees, squirrels).
Desirable Wildlife Plant
Every tree could be construed to have wildlife value, but those listed here are especially useful because they provide an easy food or shelter source.
A Shade Tree User Manual. TreeFinder, A Tree Selection Guide.
Pacific Gas and ElecTric Company.
Gilman, E.F., H.W. Beck, D.G. Watson, P.Fowler, and N.R. Morgan.1993.
Southern trees. An expert system for selecting trees. (DOS) University of Florida and USDA Forest Service Southern Region.
Michael T. Benjamin, Mark Sudol, Laura Bloch and Arthur M. Winer
Low-Emitting Urban Forests: A Taxonomic Methodology for Assigning Isoprene and Monoterpene Emission Rates. Atmospheric Environment. Vol.30, No.9, pp.1437-1452, 1996.
UC Forest Products Laboratory
Vegetation Guide for Landscaping in High Fire Risk Areas, 1997.