What Is A Tanoak Tree – Tanbark Oak Plant Info

By: Teo Spengler

Tanoak trees (Lithocarpus densiflorus syn. Notholithocarpus densiflorus), also called tanbark trees, are not true oaks like white oaks, golden oaks or red oaks. Like oak trees, the tanoak bears acorns that are eaten by wildlife. Read on for more information about the tanoak/tanbark oak plant.

What is a Tanoak Tree?

Tanoak evergreen trees belong to the beech family, but they are considered an evolutionary link between oaks and chestnuts. The acorns they bear have spiny caps like chestnuts. The trees are not small. They can grow to 200 feet tall as they mature with a trunk diameter of 4 feet. Tanoaks live for several centuries.

Tanoak evergreen grows in the wild on the West Coast of the country. The species is native to a narrow range from Santa Barbara, California north to Reedsport, Oregon. You can find the most specimens in the Coast Ranges and the Siskiyou Mountains.

A persistent, versatile species, tanoak grows a narrow crown when it is part of a dense forest population, and a wide, rounded crown if it has more room to spread out. It can be a pioneer species – rushing in to populate burned or cut areas – as well as a climax species.

If you read up on tanoak tree facts, you find that the tree can occupy any crown position in a hardwood forest. It can be the tallest in a stand, or it can be an understory tree, growing in the shade of loftier trees.

Tanoak Tree Care

Tanoak is a native tree so tanoak tree care is not difficult. Grow tanoak evergreen in mild, humid climates. These trees thrive in regions with dry summers and rainy winters, with precipitation ranging from 40 to 140 inches. They prefer temperatures around 42 degrees Fahrenheit (5 C.) in winter and no more than 74 degrees F. (23 C.) in summer.

Although tanoak’s large, deep root systems resist drought, the trees do best in areas with considerable rainfall and high humidity. They grow well in the areas in which coastal redwoods thrive.

Grow these tanbark oak plants in shady areas for best results. They do not require fertilizer or excessive irrigation if planted appropriately.

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Plant Profile: Tan Oak (Notholithocarpus densiflorus aka Lithocarpus densiflorus)

Tan oak is an evergreen shrub or tree native to western US from Oregon to California where it grows on dry, rocky slopes and in chaparral. It is a member of the beech family, Fagaceae, that also includes chestnuts. The thick, leathery leaves are three to six long and are shiny light green with whitish undersides. They are coarsely toothed and covered with orange-brown hairs when young. Upright catkins two to four inches long of small male flowers that are white before tuning rust colored appear from late spring to early summer. Inconspicuous yellow-green female flowers are produced at the base of the catkins and give way to small clusters of one inch long egg-shaped acorns that require eighteen months to mature. Each acorn has a saucer-shaped cup with dense spines and a woody nut shell. Although eaten by squirrels, the nuts are very bitter and Native Americans leached them before grinding them into flour. Useful as a specimen, hedge, screen, or in borders and woodland gardens. The genus name Notholithocarpus comes from the Latin word nothus meaning false, and the Greek words lithos meaning stone, and karpos meaning fruit, referring to the acorn. The specific epithet, densiflorus comes from the Latin words densus meaning dense or crowded, and florus meaning flowered.

Type: Evergreen tree or shrub

Outstanding Feature: Foliage

Form: Conical to rounded

Growth Rate: Slow

Bloom: Upright catkins two to four inches long of small male flowers, white before tuning rust colored, from late spring to early summer inconspicuous yellow-green female flowers produced at the base of the catkins

Size: 10-130’ H x 20-30’ W

Light: Full sun, partial shade

Soil: Fertile, moist, well-drained somewhat drought tolerant once established.

Hardiness: Zones 7-10

Care: Low maintenance

Pests and Diseases: Very susceptible to by “sudden oak death” (Phytophthora ramorum),

Seed (acorn)


Scientific nameQuercus douglasii Hook. & Arn.

Common namesBlue, white, mountain, rock, iron, post, jack, Douglas

HeightUsually 20-60 ft. tallest over 90 ft.

Mature Tree DBH (Diam. at Breast Ht.)Less than 1 ft., up to 2 ft. largest over 6 ft

LongevityLong-lived, 175-450 yrs.

AcornMatures first year variable in shape warty scales Cup very shallow

Shade ToleranceSeedlings not tolerant

SproutingVariable sprouter not vigorous on dry sites.

SitesHot, dry sites with rocky soils, 12-40 in. deep can’t compete with live oak on better sites

FoliageDeciduous blue-gray color smooth or slightly to deeply lobed edges 1-3 in. long and 1/2-2 in. wide.

Fire ToleranceTolerates grass fires not hot brush fires

Elevation500-2000 ft. in north up to 5000 ft. in south

356 year old Blue Oak Round from SLO County

AssociatesGrades into open valley oak stands at low elevations blends into denser live oak stands at higher elev. foothill pine common

Identification NotesConfused with valley oaks when leaves are dust

Scientific nameQuercus lobata Nee

Common namesValley, white, California white, mush, water, swamp, roble

Height40 to 120 ft.

Mature Tree DBH (Diam. at Breast Ht.)1-4 ft. largest over 8 ft.

LongevityLong-lived, 200-250 yrs.

AcornMatures first year, variable but large and tapered, cup over 1/3 of nut and warty

Shade ToleranceSeedlings somewhat tolerant, mature trees intolerant

SproutingNot a vigorous sprouterVariable sprouter not vigorous on dry sites

SitesPrefers fertile, well-drained bottomland soils, streambeds, and lower foothills

FoliageDeciduous leaves leathery with shiny, dark green-yellow above and grayish below deep irregular lobes 2-4 in.

Fire ToleranceNot tolerant of fires

Elevation500-800 ft. in north up to 5600 ft. in south

AssociatesBlue and Oregon white oak sometimes interior live oak

Identification NotesConfused with Oregon white oak but acorns pointed with warty cups Seedlings not tolerant

Scientific nameQuercus garryana Dougl

Common namesGarry oak, white oak, Oregon oak

Height50 to 80 feet

Mature Tree DBH (Diam. at Breast Ht.)2-3 ft. largest over 5 ft.

Longevity100-200 years

AcornMatures first year 1 in. long with shallow cup

SproutingExcellent sprouter

Shade ToleranceIntermediate tolerance as seedling and intolerant as tree matures

SitesCool humid sites near coast to hot, dry sites inland

FoliageDeciduous 4-6 in. long evenly and deeply lobed with rounded leaf tips lustrous dark-green and shiny above and pale green below

Fire ToleranceMaintained in open stands by regular, low-intensity fires

Elevation500-3000 ft.

AssociatesDouglas-fir and mixed evergreen forests Pacific madrone and tanoak

Identification NotesCan be distinguished from valley oak by acorns

View Oregon White Oak Woodland habitat information on CNPS website

Scientific nameQuercus engelmannii Greene

Common namesEngelmann, mesa

Height20 to50 feet

Mature Tree DBH (Diam. at Breast Ht.)1-2 feet

Longevity100-200 years

FoliageConsidered deciduous but foliage may persist during winter similar toblue-gray color of blue oak

AcornMatures first year

SproutingVariable sprouter

Shade ToleranceSeedlings tolerant, mature trees intolerant

SitesWarm, dry fans and foothills

Fire ToleranceVery tolerant of hot fires

ElevationUnder 4000 feet

AssociatesIn pure stands and with coast live oak

General NotesVery limited range in southern California makes protection a high priority

View Englemann Oak Habitat information on CNPS website

Scientific nameQuercus agrifolia Nee

Common namesCoast live oak, California live oak, encina

Height20 to 40 feet may reach 80 feet

Mature Tree DBH (Diam. at Breast Ht.)1-4 feet

LongevityLong-lived, 125 to 250 years

AcornMatures first year 3/4 to 2-3/4 in. cup over 1/3 of nut and not warty

SproutingVery vigorous sprouter

Shade ToleranceShade tolerant throughout life

SitesCommon on valley floors or not-too-dry fertile slopes

FoliageEvergreen 1-3 in. roundish dark and shiny above with gray or rusty fuzz underneath cupped or spoon-shaped

Fire ToleranceVery tolerant of hot fires due to thick bark

ElevationBelow 3000 ft. in north and up to 5000 ft. in south

AssociatesForms pure stands also grows with interior live oak and coast live oak

Identification NotesConfused with interior live oak but rounded and cupped leaves

Scientific nameQuercus wislizeni A. DC.

Common namesInterior live oak, highland live oak, Sierra live oak

HeightUsually 30-75 ft. shrub form 8-10 ft.

Mature Tree DBH (Diam. at Breast Ht.)1 to 3 feet

Longevity150 to 200 years

AcornMatures second year very slender, pointed, 1 in. long cup over half the nut

SproutingVery vigorous sprouter

Shade ToleranceSomewhat shade tolerant

SitesWide range, from valleys to foothills moister areas than blue oak

FoliageEvergreen with smooth to very spiny-toothed dark green above and lighter below with waxy/shiny surface 1-4 in. flat

Fire ToleranceNot very tolerant, but sprouts well after fire

ElevationBelow 2000 feet in north and above 6200 feet in south

AssociatesIn pure stands or mixed with blue and/or coast live oak, and valley oaks in So. California

Identification NotesConfused with coast live oaks distinguished by flat leaves

View Interior Live Oak Chaparral habitat information on CNPS website

View Interior Live Oak Woodland habitat information on CNPS website

Scientific nameQuercus chrysolepis Liebm

Common namesCanyon live oak, canyon oak, gold cup oak, live maul, maul oak, white live oak

Height60 to 80 feet

Mature Tree DBH (Diam. at Breast Ht.)1-4 ft largest over 5 feet

LongevityUp to 300 years

SproutingVariable sprouter

Acorn1-1/2 in. long thick, shallow cup

FoliageEvergreen 3 in. long persist 3 or 4 seasons on tree usually not lobed leathery

Shade ToleranceTolerant of shade

Fire ToleranceSensitive to hot fires

Elevation300 to 5000 feet

AssociatesFound with mixed conifer, chaparral, and woodland species tanoak, Douglas-fir, Pacific madrone, coast live oak

SitesMost widely distributed oak in CA. sheltered north slopes and steep canyons

Identification NotesBoth a shrubby and tree form very dense wood

View Canyon Live Oak Chaparral habitat information on CNPS website

View Canyon Live Oak Forest habitat information on CNPS website

Scientific nameQuercus kelloggii Newb.

Common namesBlack, California black oak

Height60 to 90 feet

Mature Tree DBH (Diam. at Breast Ht.)1 to 4 feet

Longevity100-200 yrs., occasionally up to 500 years

AcornMatures second year 1-1/2 in. long thin cup over half the nut

SproutingExcellent sprouter

Shade ToleranceIntermediate tolerance as seedling and intolerant as tree matures

SitesMore common on forest sites found on moister hardwood rangelands well-drained soils

FoliageDeciduous 5 in. long 5-7 lobed spiny leaf tips dark yellow-green above and pale yellow-green below

Fire ToleranceVery sensitive to cambium being killed in hot fires

Elevation200 to 6000 feet

AssociatesMost common with tanoak, madrone, mixed conifer forest species, also with coast live oak, interior live oak, and blue oak

General NotesProtected by Forest Practice Act on timberlands commercial properties for finished lumber

View California Black Oak Forest habitat information on CNPS website

Tanoak Evergreen Trees: Tanoak Tree Facts And Care - garden

I am looking for small or medium tree that can stay evergreen in zone7.

- Holly tree
-Southern magnolia
-Sweet bay magnolia
-Big leaf magnolia
-madrone ( although I think it has to be protected for zone 7)

FWIW, big leaf magnolia (magnolia macrophylla is generally NOT evergreen). IF you are in the PNW (if you're not the madrone (arbutus menziesii) may not be a happy tree.

some other trees/large shrubs that can be trained as trees to possibly consider:
English laurel/prunus lauracerasus
Portugal laurel/p. lusitanica
Carolina cherry-laurel/p. caroliniana
holly oak/quercus ilex
canyon live oak/q. chrysolepis
Japanese live oak/q. myrsinifolia
silverleaf oak/q. hypoleucoides
wax myrtle (either the western myrica californica or the eastern m. cerifera
strawberry tree/arbutus unedo
"red neck rhododendron"/daphniphyllum macropodum
eucalyptus neglecta
photinia serratifolia (and p. x fraseri/"red tip" too often used as a hedge but makes a nice small tree)
viburnum tinus
v. rhytidophyllum
myrtlewood/umbellularia calfifornica
tanoak/lithocarpus densiflorus
henry tanoak/l. henryi (very rare but a wonderful tree with lush "tropical" looking foliage).

a good book on evergreen trees for a variety of areas is "trees for all seasons" by Sean Hogan.

FWIW, big leaf magnolia (magnolia macrophylla is generally NOT evergreen). IF you are in the PNW (if you're not the madrone (arbutus menziesii) may not be a happy tree.

some other trees/large shrubs that can be trained as trees to possibly consider:
English laurel/prunus lauracerasus
Portugal laurel/p. lusitanica
Carolina cherry-laurel/p. caroliniana
holly oak/quercus ilex
canyon live oak/q. chrysolepis
Japanese live oak/q. myrsinifolia
silverleaf oak/q. hypoleucoides
wax myrtle (either the western myrica californica or the eastern m. cerifera
strawberry tree/arbutus unedo
"red neck rhododendron"/daphniphyllum macropodum
eucalyptus neglecta
photinia serratifolia (and p. x fraseri/"red tip" too often used as a hedge but makes a nice small tree)
viburnum tinus
v. rhytidophyllum
myrtlewood/umbellularia calfifornica
tanoak/lithocarpus densiflorus
henry tanoak/l. henryi (very rare but a wonderful tree with lush "tropical" looking foliage).

a good book on evergreen trees for a variety of areas is "trees for all seasons" by Sean Hogan.

for the sake of clarity, this (incomplete and tentative) list does not mean that all of them will do well wherever you are and anywhere on your property you choose to plant it. especially in the colder areas or microclimates of USDA zone 7 many "BLE'S" may benefit to a greater or lesser degree from being planted in a spot sheltered against cold winter winds or at least as small newly put in plants given some protection (mulching around the base of the plant, covering the entire plant temporarily) against really cold periods during their first couple of years.

some plants that really like a "west coast" zone 7 (wet winters but dry summers) like the madrones and strawberry trees or some western natives like lithocarpus densiflorus and canyon live and holly oak for example will probably not be happy in an "east coast" zone 8 (warm humid, moist summers). OTOH, the daphnophyllum, Carolina cherry-laurel, some forms of the English laurel (schipka for example), Japanese live oak (perhaps even some forms of the southern live oak/q. virginiana), the eastern wax myrtle and others either on or not on this list may be much more adaptable. the eastern native holly ilex opaca may be better for the east than the English holly I. aquifolium and so on.

FWIW, some folks in favorable microclimates and sometimes with protection in the worst winters have successfully grown palm trees like trachycarpus fortunei or sabal minor for a little extra exotic "pop" in their gardens.

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Grassy fuels on the forest floor were not the cause of frequent prehistoric fires in giant sequoia (Sequoiadendron giganteum) groves, according to UC Berkeley researchers and California State Park ecologists. Learn more about this research.

Thinning Speeds Recovery to Old-Growth

Dr. Christopher Keyes and Andrew Chittick have found that thinning—removing select trees in a second-growth coast redwood forest—speeds up the forest’s development of old-growth characteristics, which include tall and bulky trees, small gaps in the canopy through which sunlight can penetrate, trees of varying heights, thicker tree branches, understory shrubs and ferns, and healthy young saplings. Learn more about this research.

Land Use and Forest Conservation

Dr. Sarah Marvin, professor of Geography at the University of Oregon, has set out to understand how the shape of the land and its use by owners reflect the probability of a privately owned coast redwood forest being protected. The two questions she has asked are: “Are privately owned forests more likely to be protected if they are on bigger parcels?” and “Do traditional, rural land uses as opposed to traditional, residential land uses promote forest preservation?” Answers to these questions might help predict the likelihood of future, private redwood forest protection and—of logged forests—regeneration. Learn more about this research.

Chemicals in Redwood Rings Indicate Past Water Uptake

It’s no coincidence that redwoods live in the thickest part of “California’s fog belt.” The presence of coastal summer fog has long been regarded a necessary ingredient for the health and perpetuation of coast redwood ecosystems. During drier summer months fog supplies trees with moisture and blocks the evaporating rays of direct sunlight, reducing the amount of water that redwoods lose via transpiration. What’s less understood, however, is exactly how fog frequency has varied in the past century and how redwoods have responded to this variation. Learn more about this research.

Bigger and Older Often Means Better Habitat

Traditionally we think of forest conservation as protection of large areas of land. Is it possible, though, that just one tree could benefit an ecosystem enough to warrant individual protection? Mary Jo Mazurek and William Zielinski report evidence that suggests legacy old-growth redwoods can do just that. Learn more about this research.

Big Trees: A Bank for Soil Bugs

Legacy trees, old-growth trees left standing in second-growth redwood forests, could serve as a habitat refuge for terrestrial microarthropods, miniscule bugs that live in the forest floor and maintain healthy soils, not to be confused with the bigger arthropods like spiders and bees. Dr. Michael Camann, Karen Lamoncha and Laura Hagenhauer have found substantially more and a wider variety of the soil bugs underneath these so-called legacy trees than beneath surrounding second-growth trees. Learn more about this research.

Bats in Giant Sequoias

Prior to this study, little was known about the bat community in Yosemite’s three giant sequoia groves and virtually nothing was known about how bats use the canopy in any of the Parks’ forests. Dr. Elizabeth Pierson, Dr. William Rainey, and Leslie Chow carried out major research to study bat roosting behavior in fire-scarred hollows at the base of sequoia trees, bat feeding behavior in association with a variety of habitats, and bat activity in the giant sequoia canopy. In addition, they combined observations from this study and others to describe the natural history of Yosemite’s 18 bat species. Learn more about this research.

Redwoods to the Sea Forest Carnivore Tracking Project

From time to time, a resident in Humboldt County will submit a report claiming to have spotted a Pacific fisher or a Humboldt marten. Because Pacific fishers are rare, and because the Humboldt marten was previously thought to be extinct due to human influences such as trapping and logging in their old-growth conifer habitat, these animals remain barely documented. The Corridor from the Redwoods to the Sea, built as a passageway for wild creatures, appears to be prime location to spot small carnivores such as fishers and martens, but despite local accounts, the rare sightings remain unverified by scientists. Where have these small predators gone? Learn more about this research.

Buffer and Let Be

Dr. William Russell found that the negative effects of timber harvesting in riparian coast redwood forests lessen with respect to two conditions (1) longevity of the forest and (2) wider no-cut buffer zones. Longer-lived forests and forests with wider buffer zones surrounding rivers show less harm from logging. Riparian buffers are strips of forest left on either side of rivers after logging that control the amount of sediment and nutrients filtering into the water. In recently harvested forests and ones with thin or no buffers, young tree crowns crowd the canopies, letting through less sunlight, deciduous hardwoods thrive, extra dead wood litters the forest floors, and exotic and disturbance-prone understory species invade. These alterations, in addition to affecting the physical structure of rivers, down the line cause higher levels of organic material to filter into them. Learn more about this research.

Humboldt Martens Need Old Growth

It’s likely that Pacific fisher (Martes pennanti pacifica) populations are well distributed in Northern California’s Redwood National and State Parks (RNSP) for the same reason that Humboldt martens (Martes americana humboldtensis) have disappeared, according to research done by Keith Slauson, William Zielinski, and Gregory Holm. Second-growth forest habitats that cover a majority of the park are fishers’ sweet and martens’ sour. Learn more about this research.

Wandering Salamanders Choose Direct Route to Good Food

Wandering Salamanders (Aneides vagrans), in addition to dwelling on the ground, have been found in high-up patches of humus moss mats in trunk crotches, on limbs, under bark, and in the cracked and rotting wood of coast redwood trees. They may inhabit forest canopies, the researchers of this study speculate, because of a more profitable food resource available there. Learn more about this research.

What limits redwood height?

In the upper reaches of their crowns, coast redwoods struggle to lift water and nutrients into their leaves. This struggle begins a process that limits tree growth, according to a team of researchers studying redwoods in Prairie Creek and Humboldt Redwoods State Parks. Learn more about this research.

Sponge-like Mats Make Good Habitat in Redwood Canopies: Wandering Salamanders Benefit

Based on their research in Pairie Creek Redwoods State Park, Anthony Ambrose and Stephen Sillett have found that mats of humus soil deposited as high up as 265 feet in the crowns of coast redwood trees moderate the climate around them. This makes the mats habitable to a wide variety of insects and animals more commonly found on the forest floor. Learn more about this research.

Giant Sequoia Ecology Cooperative Web Site

Finding scientific resources on a specific plant species like the giant sequoia can be a daunting task. From the tangled network of information on the World Wide Web, the Giant Sequoia Ecology Cooperative Web site provides quick resources, ranging from maps and informational documents to expert contacts, which link the world to data on this rare tree, found only along the western slopes of the Sierra Nevada. Learn more about this research.

Balanced Management of Giant Sequoias

Giant sequoias are sometimes simply referred to as “big trees” and with good reason: They are the largest trees by volume and among the largest living things on Earth. These massive trees do not function in a void they are supported by an intricate network of natural processes that keep the ecosystem working properly. Learn more about this research.

Coast Redwood May be the Descendent of Two

Dr. Raj Ahuja and Dr. David Neale have taken a big stride in coming closer to knowing the origin of polyploidy in coast redwood. Learn more about this research.

Epiphytes Provide High-Up Base for Biodiversity

William Ellyson and Stephen Sillett found evidence that demonstrates that epiphytes—plants that use other plants for mechanical support—play a crucial role in maintaining the biodiversity of redwood forest canopies. It’s well known that these hangers-on thrive in the old-growth Douglas-fir forests of Oregon and Washington, in places amassing the weight of two concert grand pianos per acre. Ellyson and Sillett reveal in this study that Douglas-fir has a rival in Sitka spruce, a tree that grows in and among northern coast redwood forests and supports a shockingly high diversity of epiphytes. Learn more about this research.

Bigger Preserves Have Better Chance to Prevail

Dr. William Russell, Dr. Joe McBride, and Ky Carnell have found that old-growth coast redwood forest reserves with areas larger in proportion to the length of their perimeters suffer fewer negative effects from exposed edges. Learn more about this research.

Bibliography Provides Easy Access to Coast Redwood Research

Coast redwoods have captivated scientists since their discovery, and thousands of articles, dissertations, and books have been written in an attempt to decipher various aspects of these magnificent trees. Finding all of this information was considerably more challenging until Deborah Rogers, a research geneticist and conservation biologist with the Genetic Resources Conservation Program at the University of California, Davis, stepped in to organize a bibliography of scientific materials written about coast redwoods in the past 50 years. Learn more.

Tree Encyclopedia

Trees have three principle features that distinguish them from all other plants. First, they have a woody stem, roots and branches which do not die back in winter, but continue to grow year after year. From the moment of its germination, a tree remains visible from the tallest Sequoia to the smallest garden fruit tree, this principle of growth remains constant.

Trees live longer than any other organism on earth. Trees commonly live more than 1,000 years, and many grow considerably older. A bristlecone pine, Pinus longaeva, at Schulman Grove in California has been documented both by core drilling (a pencil-thin core is taken from the tree’s trunk, and the rings are counted) and by carbon-dating as being 4,700 years old. Third, trees are the largest organisms on the planet. Around the world are found many single trees in excess of 100 meters tall, weighing more than 1,500 tons (6,600,000 kilograms).

Pando (Latin for “I spread”), aka “the trembling giant,” is a clone colony of male quaking aspen, (Populus tremuloides) a single living organism identified by identical genetic markers. Assumed to have one massive underground root system, the plant is estimated to weigh 6,000,000 kg (13,227,735 pounds) making it the heaviest known organism of any kind. Estimated at 80,000 years old, Pando is also the oldest living organism on Earth. Pando is located in the Fishlake National Forest in South-Central Utah [6].

Trees have been living on Earth for more than 370 million years, and today can be found almost everywhere from the Arctic Circle to the Sahara Desert. Worldwide, trees are almost always the climax species of all plants – which means unattended land will eventually host trees. -Trees Index-

Family Aceraceae: Maples are some of our most familiar and beloved trees. They are famous for their fall colors, from vivid crimsons, vibrant yellows to blaze orange and all shades in between. Most are native to the far east: China, Japan, Korea, Manchuria. Maples produce a distinctive winged fruit called a samara, also commonly known as helicopters or whirlybirds. A single mature sugar maple can produce 4 tons of seeds each season.

NASA thoughtfully provides instructions on constructing a helicopter out of paper: “Maple seeds are superb autorotating helicopters. They begin rotating almost from the moment they are released from the tree. Even seeds that are poorly shaped or have badly damaged blades (wings) rotate with ease.”

Family Adoxaceae: Viburnum
This family of woody plants consists of five genera: Adoxa, Sambucus, Sinadoxa, Tetradoxa, and, most notably, Viburnum. Many of these plants were formerly placed in Caprifoliaceae. Viburnums have long been cultivated by gardeners fond of flowering landscape shrubs. There are over 150 varieties readily available to suit practically any locale – wet or dry sites, partial shade or sun. Hardy in USDA zones 2 through 9.

Viburnums were up until recently relatively pest and disease-free, which accounted for their popularity with home gardeners. However, the Viburnum leaf beetle is making inroads in North America, infesting highbush cranberry viburnum, arrowwood viburnum, and others. -Trees Index-

Family Anacardiaceae – Cashew, Sumac, Pistachio, Mangos, Poison Ivy Trees or shrubs each with small flowers, highly poisonous sometimes foul smelling resinous or milky sap. There are about 600 species in 70 genera. Important commercial crops in this family include the cashew and pistachio nuts and mangos. Resins, oils and lacquers are obtained from plants in genus Toxicodendron. Poison ivy is undergoing an explosive surge in range, prevalence, and toxicity worldwide, due to the particular effects of increased CO2 concentrations in Earth’s atmosphere.

Family Araliaceae – Ivy or Ginseng Family
The Araliaceae comprise about 70 genera and 700 species of flowering shrubs, trees, climbing vines and herbs.

Family Betulaceae – Alder, Birch, Hornbeam
The birches have long been popular ornamental trees in North America, chiefly in the northern United States and Canada. Several are native Americans, but many species have been introduced from Europe and Asia. Our specimens include river birch, Dahurian birch, paper birch, Arctic birch, Manchurian birch, Manchurian alder, downy birch, Japanese white birch, and 10 other species.

Family Cupressaceae Redwood, Cypress, Arborvitae, Juniper
There are thirty (many monotypic) genera and 142 species in the family Cupressaceae, now widely regarded as including the Taxodiaceae, previously treated as a distinct family. The Cupressaceae are found in the fossil record as far back as the Jurassic Period, about 210 million years ago.

The heartwood of many species of Cupressaceae is resistant to termite damage and fungal decay, and therefore it is widely used in contact with soil. Most prominent in the flora are redwood and baldcypress the premier coffin wood of China. Other genera, usually called cedars, may have aromatic woods with a variety of specialty uses. Wood of Thuja is still used for roofing shingles.

Family Fabaceae: Legumes are mostly herbs but include also shrubs and trees found in both temperate and tropical areas. They comprise one of the largest families of flowering plants, numbering some 400 genera and 10,000 species. Peanuts, beans, peas, clover, alfalfa, wisteria and locust trees are among the family.

Legumes harbor nitrogen-fixing bacteria in nodules in their root structures. Legumes comprise the vast majority of pioneer plant species because of their ability to survive in soil with few nutrients, e.g. the area around the 1980 explosion of Mount Saint Helens lupines were the first plant life found in the superficially sterilized wasteland of volcanic ash downstream from the crater.

Family Fagaceae – Beech, Chinkapin and Oak
There are about 900 species in this family worldwide, about 65 trees and 10 shrubs of which are native to North America. The Oak genus,Quercus, includes some of our most important native hardwoods, and are some of the most-recognized trees. Since the early 1990s, oak and tanoak have been dying in the coastal counties of California [1]. Sudden oak death, caused by the pathogen Phytophthora ramorum is now expanding its range in coastal California and Humboldt County, killing millions of trees.

We’ve photographed over twenty species of Oaks, Chinkapins and Beeches at the Morton Arboretum, as well as the State of Illinois Millennium Tree, and another Bur Oak that is known to be still healthy and injury-free after more than three hundred years.

Family Hamamelidaceae: Witch Hazel Family
The Witch hazel family is comprised of 23 genera of shrubs and trees native to both tropical and warm temperate regions. It includes popular ornamentals such as witch hazel, winter hazel, fothergilla (witchalder), sweet gum, and ironwood trees. -Trees Index-

Family Hippocastanaceae – Horse-Chestnut, Buckeye
Members of this family are trees or shrubs, usually deciduous. Most widespread genus is Aesculus. One distinctive feature is the palmate compound leaves. Three genera and 15 species: Asia (Himalayas to Japan), SE Europe, North America, also Central and South America two genera (one endemic) and five species (two endemic, two introduced) in China. Young shoots and seeds of yellow buckeye have been reported poisonous to livestock, and some landowners in Indiana have eradicated buckeye for this reason.

Family Juglandaceae – Walnut, Hickory, Butternut, Bitternut, Pignut, Pecan
Members of this family have large aromatic leaves. The trees are wind-pollinated, and the flowers usually arranged in catkins. Hickory nuts and Walnuts grow within an outer husk these fruits are technically not nuts, but drupes. There are eight genera in the family, including the commercially important nut-producing trees: walnut, pecan hickory, and hickory. The Persian walnut (Juglans regia) is one of the major nut crops of the world. Walnut and hickory are valuable timber trees.

Family Laurelaceae – Laurel Family is comprised of 2000 – 4000 species in 55 genera of flowering plants in the Order Laurales. Most are aromatic evergreen trees or shrubs, but Sassafras and one or two other genera are deciduous, andCassytha is a genus of parasitic vines.

Members of this family are generally aromatic shrubs and trees with insignificant flowers and fleshy fruit. Some of the better known members of the family are the avocado, camphor tree, cinnamon, sassafras, and spicebush. However, the “prime” member of this family is the Bay Laurel (Laurus nobilis), famous as the provider of bay leaves for cooking, also a useful hedging plant, and the source of branches from which laurel wreaths were created. “Don’t rest on your laurels.” -Trees Index-

Family Magnoliaceae – Magnolia. The Magnolia genus is one of the most ancient among flowering trees. Growing to 30 meters, cucumber tree is the most widespread and hardy of the eight magnolia species native to the United States, and the only magnolia native to Canada. Several species in the family are grown for their dried flower buds, known as xinyi, which are used medicinally. Houpoea officinalis(Magnolia officinalis) is extensively grown for its medicinal bark. All species in the family are ornamental, and many are grown in public and private gardens throughout much of China and in other parts of the world.

Family Moraceae: Figs and Mulberry. Trees, shrubs, herbs or vines, both evergreen and deciduous mainly woody and tropical, they are most abundant in Asia. The largest genus is Ficus, with about 750 species of figs. Species bearing edible fruit include the mulberries, breadfruit and jackfruit. Although weeping figs and rubber plants are often sold as houseplants, economically the most important species are related to the silk trade they serve as food plants for the silkworm, Bombyx mori.

Olive Family: Oleaceae The olive family contains 25 genera and over 500 species of flowering plants. Most species are native to temperate and tropical regions of the Northern Hemisphere. The best known trees of this family are olive and ash, while the most familiar shrubs are privet, lilac, and golden bell (Forsythia), all popular ornamental plants. -Trees Index-

Family Pinaceae – Pine, Cedar, Spruce, and Fir The Pine family is the most varied of all the groups of trees that bear cones. Pinaceae contains more than 250 species which are native and which form the dominant forest cover over much of the northern hemisphere.

Family Rosaceae – Fruit Trees, Roses: Hawthorn, Apple, Pear, Cherry, Plum, Peach, Almond, Mountain-Ash and White- beam. The Rose family is a large assemblage of trees, shrubs and herbs including many of our most familiar and valued fruits, the drupes and pomes. Of course, the family is named for the type genus, Rosa, which contains perhaps the best known and loved flowers on Earth, the roses. The fruits come in many varieties and were once considered the main characters for the definition of subfamilies. They can be follicles, capsules, nuts, achenes, drupes (cherries and apricots) or accessory fruits, like the pome of an apple.

Family Rutaceae – Cork & Citrus Trees The Rutaceae are herbs, shrubs, and trees with commonly odoriferous herbage comprising about 150 genera and 1,500 species further characterized by the common occurrence of spines and winged petioles. The Citrus genus includes the agriculturally important fruit trees: orange, lime, grapefruit, kumquat, and mandarine.

Family Salicaceae – Aspen, Willow, Cottonwood, Poplar There are only two genera in this family, Salix (willows), with about 300 species, and Populus (aspens and poplars), with barely 40 species. Salicaceae are found throughout the temperate parts of the world, with the majority of species occurring in the north. Both willows and poplars have a strong affinity for water, and are commonly found near ponds and along watercourses.

Family Taxaceae – Yews There are 17 species in five genera 5 in this small family. The Yews are evergreen trees or shrubs, usually not resinous or aromatic. The Taxaceae are now generally included with all other conifers in the order Pinales.

Family Tiliaceae – Basswood, Linden 50 genera and 400 species widespread in tropical and subtropical regions, with relatively few species in temperate regions. Especially abundant in Southeast Asia and Brazil. Lindens are called Lime trees in Great Britain and The Commonwealth. The leaves of all the Tilias are heart-shaped and most are asymmetrical, and the tiny fruit, looking like peas, always hang attached to a ribbon-like, greenish bract, whose use seems to be to launch the ripened seed-clusters just a little beyond the parent tree.

Lindens are some of the most popular shade and street trees in North America. Their pyramidal forms are eminently suitable for specimen plantings.

Family Ulmaceae – Zelkova, Hackberry and Elm There are about 200 species of trees and shrubs in Ulmaceae. 14 trees and 2 shrubs are native to North America. The Elms fell victim to Dutch Elm disease during the 1950s until that time, they were the premiere shade tree along the streets of our towns and cities. The Morton Arboretum is one of the largest living Ulmus collections in the world (more than 30 species, in addition to numerous infraspecific taxa, hybrids, and cultivars) and has the source of numerous elm cultivars. We present here more than 20 different species from this outstanding collection.

Orphan Species Here are trees that represent only one or two species and do not merit their own family pages.

Tree Encyclopedia / North American Insects & Spiders is dedicated to providing scientific and educational resources for our users through use of large images and macro photographs of flora and fauna.

Tanoak and Coast Live Oak Under Attack

Oaks ‘n’ Folks – Volume 14, Issue 2 – August 1999

Tanoak (Liuthocarpus densiflorus)and coast live oak (Quercus agrifolia)distribution stretches more than 1,500 miles along the California and Oregon coasts. Coastal forests are not monocultures but rather full grown islands of different species that cover like ribbons the California and southern Oregon shoreline. However, since 1995 scattered patches of dying tanoaks around the Mount Tamalpais-Inverness area have provided a hint of the serious threat to their existence.

What actually does happen? Tanoaks, very resilient trees, suddenly die. The symptoms are puzzling: a mature tree’s shoots display very pale green color then suddenly droop. Old foliage changes from dark green to light green, then suddenly the whole crown is brown with leaves clinging to the branches for the remainder of the growing season. Development of these symptoms and sudden death occurs within 4 to 6 weeks. Such a progression of symptoms and rapid death of evergreen trees caused by any pathogen has never before been recorded. Only a potent chemical, such as a phenoxy-based herbicide could mimic similar rapid death. During the following growing season tanoaks lose their leaves leaving bleached twigs and branches as a testimony of the onslaught.

However, the sudden massive death of tanoak has not worried foresters, because they consider tanoak an “undesirable weed,” claiming space from other species that are economically important for lumber. Yet for people who live in the urban forest interface this tree provides shelter and other ornamental amenities. For homeowners in the California coastal region, the tanoak shades houses and shelters other tree species with its resiliency to withstand storms. For example, the coast live oak, which grows slowly in its young age but later becomes dominant, is a major benefactor of this protection, especially if the tanoak is “out of the way” in the live oak’s mature stage. The sudden death of tanoak would then be helpful to achieve more desirable live oak, but there is a worrisome development: tanoaks have become heavily attacked by oak bark and ambrosia beetles. In these rapidly dying tanoaks, the beetles reproduce in the millions, and have unleashed an epidemic of unprecedented proportions in coast live oaks grown as ornamentals and in natural forests. Again, such massive dieback of live oaks was never recorded in California and, if this rate continues, we are going to face a double environmental crisis: (a) loss of these highly valued trees from gardens and forests, and (b) serious fire hazard risk from the resulting build-up of dry fuel.

Since 1995 dying tanoaks and live oaks have been sampled to determine the cause of this unusual and rapid death. So far, only a single common relationship exists-bark beetles and the more visible ambrosia beetles are always present. However, the triggering factor, which invites these beetles to arrive and kill the tree, has yet to be discovered. Therefore, I have developed two publications that describe the current situation and offer some avenues that may help to find the biotic or abiotic factor that initiates the rapid death of tanoaks and whether a similar mechanism will operate in coast live oaks. The rate of live oak death has reached epidemic proportions in Marin County and has now spread to Sonoma County and possibly to other coastal regions.

Pavel Svihra can be reached at the Marin County Cooperative Extension Office (415) 499-4204, and email address: [email protected]

prepared and edited by Richard B. Standiford, Justin Vreeland, Bill Tietje

Portola Valley, CA

Quercus agrifolia
Large evergreen oak, spreading, attractive branch pattern, deep green, rounded, holly-like leaves. Probably the best tree for local propagation. Bark on trunk and limbs smooth in young trees, becoming roughened and furrowed with age.

Planting : Park shade tree. Faster and better growth when planted than when inherited as seedling from nature, although the latter should be fostered. May be grouped as closely as 6' to create woodland grove. Can grow well in many kinds of soils.

Local : Examples are common. The larger evergreen in Ford Park, and two next to red schoolhouse are fine examples. Younger trees border Westridge Drive.

Quercus kelloggii

Large deciduous oak, branching high to 70’ or more, with broad, rounded top. The dark shiny leaves deeply lobed, the lobes toothed. In autumn the leaves turn yellow, sometimes very colorfully on the descending mountainside ridges. This is a mountain oak, not found here below 350’ elevation.

Planting : Becomes a large tree slowly. Best planted with other oaks for shade in early life. Local occurrence suggest well drained soil habitat.

Local : Both sides of upper Cervantes Drive between Fawn Lane and Westridge Drive, and by Alpine Road opposite Corte Madera School. Fine specimen on upper side of Bolivar Lane about 150’ from Westridge Drive. Common in Corte Madera canyon, along Alpine Road.

Quercus lobata

Large deciduous oak with lobed leaves and rough grey bark. Mature trees with beautiful tortuously spreading limbs. The large, widely spaced, deciduous oak of our grass lands.

Planting : Shade tree best as a single specimen or widely and irregularly spaced in open grassland areas. Slow growing, but it is thought to be the largest oak in America.

Local : A common tree. Old specimens may be seen with Live Oaks in Ford Park, and on the grounds south of red schoolhouse.

Sequoia sempervirens

Towering, fast-growing symmetrical tree. Leaves are dark green needles. Bark furrowed deep reddish brown on older trees. Roots spread and feed near surface which in the forest are covered by dry needlefall. Under favorable conditions in well watered areas will grow from 2’ to 5’ per year.

Planting : Needs water. Does best in partially shaded areas, and when planted in groves or circles from 10’ to 50’ in diameter. Grows rapidly. Practically pest free.

Local : May be seen at entrance to The Sequoias, and behind Ormondale School atop the creek bank. A fine grove may be seen along Portola Road at the entrance to the Morshead Ranch, “El Mirador,” and in the surrounding areas.

Watch the video: How to Grow and Care Norfolk Island Pine Tree in a Pot at Home Araucaria Heterophylla

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