Text by Doreen Smith and photos by Doreen and Vernon Smith and Susan Schlosser
Quercus douglasii : blue oak
Quercus douglasii : blue oak – Photo by Vernon Smith
In Marin this species of oak is found to the North-east of the county, around Novato and Black Point. Once the California Blue oak was the most extensively found hardwood tree in the State but now regeneration has not kept up with removal and natural mortality.
Characteristics.
Trees are 20 to 60 feet tall when mature, with trunks 2 to 4 feet in diameter.
Bark is light grey, shallowly checked and may flake.
Quercus douglasii : blue oak – Photo by Vernon Smith
Leaves are blue-green, usually shallowly lobed, about two inches long and deciduous in the fall.
Acorns mature in one year, are medium in size and are blunt-tipped in shallow warty cups.
Quercus agrifolia : coast live oak
The most common California Coast Range species of oak is also the most widely-found kind of oak in Marin. It is at home in many habitats, on hills, in valleys, in poor or good soils but not in wet places. This oak regenerates well after cutting or burning as well as from seed. Browsing animals are deterred from eating mature growth because of the stiff and holly-like leaves.
Quercus agrifolia : coast live oak – Photo by Doreen Smith
Characteristics.
Mature trees are squat and broad, typically 30 to 75 feet tall.
The short, thick trunk may be several feet in diameter, it usually branches low to the ground giving rise to a wide, spreading crown.
Evergreen leaves of medium size are dark green and shiny above, paler with axillary hairs below; the margin is characteristically spiny. Leaves are convex and cannot be flattened easily.
Acorns are medium in size, pointed at the apex, mature in one year and are borne in scaly cups.
Quercus Kelloggii : California black oak
This species of oak is widespread in Marin, usually in mixed forest and especially in sheltered ravines and on North-facing hillsides. State-wide it is found in both coastal and mountain regions. No-where is it reseeding well, perhaps due to fire-suppression conifers out-compete it in many areas.
Quercus kelloggii : California black oak – Photo by Vernon Smith
Characteristics.
The bark is dark-colored, furrowed and checked.
Leaves are large, deciduous, up to 8 inches long and four inches wide, deeply-lobed, each lobe with 1 to 4 bristle-tipped teeth. The upper surface is bright green and glossy when mature, the leaf lower surface is paler and may be hairy.
The acorns are large, borne in scaly caps and take two years to mature.
Quercus lobata : valley oak
The tallest and largest of California oaks is most commonly found on deep fertile soils and along river-banks. The value of such sites for agriculture resulted in the removal of countless trees in the past. Where the oaks remain they are becoming senescent and as they fall they are rarely replaced by seedlings due to grazing, fires, rodents and competition from introduced plants. To maintain this species of oak we have to plant and protect young trees .
Characteristics.
Quercus lobata : valley oak – Photo by Vernon Smith
Mature trees can be over 100 feet tall with trunks 10 to 13 feet in diameter at the base. The bark is grey, deeply ridged and grooved.
The trunk branches high to give a vase-shaped crown, the branches hang down at the ends.
The medium-sized leaves are lobed, bright green above, pale green on the undersides; they are deciduous in the fall.
Acorns mature in one year, they are medium to large, can have blunt or pointed tips and have very warty cups.
Quercus durata : leather oak
A shrubby oak found in serpentine, usually chaparral areas in Marin. The name comes from the leathery texture of the leaves.
Quercus durata var. durata : leather oak – Photo by Vernon Smith
Characteristics.
A shrub or small tree, up to 15 feet tall.
Scaly bark.
The leaves are greyish green, evergreen, lobed, about 1″ long, and leathery in texture.
The acorns are of medium size, tip rounded, and mature in one year. Cap has warty scales and is cup-shaped.
Quercus wislizeni : interior live oak
The most abundant and widespread oak in chaparral areas of Marin.
Quercus wislizeni var. frutescens : interior live oak
Characteristics.
Can be a shrub or tree up to sixty feet tall.
Trunk bark is dark and furrowed.
Evergreen, shiny, leaves, dark green above, often with toothed edges.
Acorns are medium with pointed tips and cup-shaped, warty caps. Ripen the second year.
Quercus chrysolepis : canyon oak
Common oak in canyons and on rocky ridges.
Characteristics.
Quercus chrysolepis : canyon oak – Photo by Vernon Smith
Quercus chrysolepis: canyon oak – Photo by Vernon Smith
Can occur as a large tree or a shrub with scaly, light-colored, furrowed bark.
Medium evergreen, pointed leaves, shiny and dark green above and dull below.
Acorns are egg-shaped, about 1″ long with saucer-shaped, scaly cup, taking two years to mature.
Quercus parvula var. shrevei : Shreve’s oak
Oak found in moist woodland and forest.
Quercus parvula var. shrevei : Shreve’s oak – Photo by Vernon Smith
Characteristics.
Tree up to ninety feet tall.
Small acorns with rounded scaly cups.
Quercus berberidifolia : scrub oak
Oak found in chaparral.
Quercus berberidifolia : scrub oak – Photo by Vernon Smith
Characteristics
Shrub or small tree, with gray, scaly bark.
Small evergreen oval leaves that can be shiny.
Small acorns with bowl-shaped cap with warty scales. Matures in one year.
Quercus garryana : Garry oak or Oregon oak
Oak found on rocky outcrops and drier meadows.
Quercus garryana : Oregon oak – Photo by Susan Schlosser
Characteristics
Shrub or small tree, with thin scaly bark.
Deciduous large oval leaves, shiny and dark green above and paler and hairy beneath.
1″ long oblong to roundish acorns with cup or saucer-shaped cap with warty scales or not. Matures in one year.