Valley oak, Blue oak and Engelmann oak are the common oaks of the inner valleys in California.

California Oaks
Acorn matures in one season (at end of new stems)	Acorn matures in two seasons (on older stems)
1. Evergreen Quercus agrifolia, Q. x alvordiana, Q.dumosa, Q. durata, Q. sadleriana, Q. turbinella	2. Deciduous Quercus garryana var. breweri, Q. douglasii, Q.engelmannii, Q. garryana, Q. lobata	3. Evergreen Quercus chrysolepis, Q. parvula, Q. tomentella, Q. vaccinifolia, Q. wislizenii, Lithocarpus densiflorus (Tanbark Oak)	4 Deciduous Q. kelloggii, Q. palmeri Oak relationship chart
How to take care of your oak trees.	Back to the front page of Las Pilitas

California Oaks

Acorn matures in one season (at end of new stems)

Acorn matures in two seasons (on older stems)

1. Evergreen

Quercus agrifolia, Q. x alvordiana, Q.dumosa, Q. durata, Q. sadleriana, Q. turbinella

2. Deciduous

Quercus garryana var. breweri, Q. douglasii, Q.engelmannii, Q. garryana, Q. lobata

3. Evergreen

Quercus chrysolepis, Q. parvula, Q. tomentella, Q. vaccinifolia, Q. wislizenii, Lithocarpus densiflorus (Tanbark Oak)

4 Deciduous

Q. kelloggii, Q. palmeri

Oak relationship chart

How to take care of your oak trees.

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2. California Oaks that bear acorns on each season's growth and are deciduous.

Blue Oak – Quercus douglasii- The Blue Oak lives from about Los Olivos in the coast ranges and Lebec in the interior and north through the coast ranges and the west base of the Sierra Nevada mountains to around Lake Shasta. This is a very drought tolerant tree; in much of its normal range the rainfall is an irregular 7-10 inches each year (same as much of the Mojave Desert). Blue Oak has bluish-tinged leaves, and the leaves are deciduous and sometimes prickly. This oak grows very slowly. We have seen some pretty large ones, however. Blue Oak is commonly a round headed, 20-30 ft. tree. Where hybrids with Valley Oak (Quercus lobata) occur (Quercus douglasii X Q. lobata or Quercus x jolonensis) you can find some huge 'Blue Oaks' that are really stable (and fertile) hybrids. There are some of the giant hybrids in west Atascadero, around Jolon, and a whole valley of them east of Pozo. You can also find hybrids with Oregon Oak (Quercus garryana) in Blue Oak's northern range. This hybrid has been called Q. x eplingii	Engelmann Oak- Quercus engelmannii is deciduous, or evergreen, depending upon environmental conditions, with lobed leaves with a bluish tinge, not prickly, a smaller round form, and very drought tolerant. This oak ranged from Pasadena to Baja usually away from the coast, but not in the desert or higher elevations. It's a flat lander, foothill or valley dweller. Not many are found as you hike through the chaparral or pine forests. It is commonly associated with the shallow rocky soils that can't support much more than bulbs, grasses, sages, buckwheats and forbs, and then Engelmann Oaks (Quercus engelmannii), Ribes spp., Rhamnus spp., and sometimes Rhus spp. make a colony in a patch of deeper soil. An Engelmann Oak (Quercus engelmannii) Leaf.
A deciduous Blue Oak declining in a weedy field.	Oregon Oak- Quercus garryana is not so drought tolerant, and grows more in the northern part of the state from about Santa Cruz north and across into the Siskiyou mountains and down into the Northern Sierra Nevada mountains.
Blue Oaks (Quercus douglasii) can have almost entire leaves.	Quercus garryana var. breweri is the scrub form of Oregon Oak called Shin Oak. It grows from the lower Sierra Nevada mountains north and along the coast ranges from about Santa Cruz northward.
Blue oaks (Quercus douglasii) hybridize with many of the other oaks in California and often you're left guessing which it is. Sometimes Blue Oaks (Quercus douglasii) and Valley Oaks (Quercus lobata) get together and you get more hybrids than 'real' trees. Sometimes Blue Oaks (Q. douglasii) and scrub oaks (Quercus berberidifolia) make a mess of little oaks that leave most of us confused and one or two newbie botanists thinking up new species names. I would be very happy if a group of botanists by consensus combined almost all the oaks into one species, with the subspecies, forms, varieties and hybrids listed under them. THEN, if you were not sure which one you were looking at you could 'go up the tree' one step. We have hillsides where Coast Live Oak (Quercus agrifolia), Valley Oak (Quercus lobata), Tucker's Oak (Q. john-tuckeri) , Blue Oak (Q. douglasii), Nuttall's Scrub Oak (Q. dumosa) , hybrids (Q. dumosa X Q. lobata, Q. dumosa X Q. douglasii, Q. john-tuckeri X Q. douglasii, and sometimes what appear to be evergreen Blue Oaks all together in an area the size of a football field. The blend and morph into each other . Almost every tree leaves you scratching your head. They cannot all be different named species, not with all the “kids” around that do not fit.	Blue Oak acorn.
More Blue Oak (Quercus douglasii) Acorns.	Had enough Blue Oak leaves? These are smooth and soft, though.
Valley Oak (Quercus lobata) Leaves. These are pointy.(Highly scientific term)	More Valley Oak (Quercus lobata) Leaves; these are nice and round.
A couple of Valley Oak (Quercus lobata) silhouettes. This tree above is 50 feet or so tall.	This tree is probably 80 feet or more high with a three foot trunk. Different hybrids (other than the Blue Oak hybrids listed above) Quercus x kinselae and Quercus x macdonaldii are hybrids of Q. lobata and Q. dumosa Then there's a hybrid of Q. lobata with Q. john-tuckerii (Quercus lobata var. insperata) Q. x munzii (Q. lobata X Q. turbinella) Q. x townei (Q. dumosa X Q. lobata) Quercus lobata has also been known to hybridize with Q. garryana and Q. kellogii (see our Q. kelloggii)