This lifeform is found from north-central California south to San Diego.

California Scrub Oak (Quercus dumosa) is found from N. Baja California to north of San Francisco. This is primarily a species of the western third of the state of California. This shrub or small tree is usually less than 18 feet tall. The leaves have several toothed indentations. The acorn is long and narrow and pointed.

Quercus genus (Oak trees) is a well-known genus found in the northern hemisphere as well as in South America and northern Africa.  Although there are about 300 to 600 species known worldwide,  only about 65 of them are found in temperate North America.  Kartesz lists 86 species, 98 hybrids, and 35 subspecies as being found in his greater North America, which includes the United States, Canada, Hawaii, Greenland, Puerto Rico and the U.S. Virgin Islands.  To facilitate study of this genus, many authors break it into halves,  red oaks and white oaks.  Typically,  the red oaks have lobes in the leaves that end in spines, while the white oaks have lobes that are rounded.  Although many of the red oaks have very pretty wood that is sometimes used for wood flooring,  the white oaks are known for a hard wood that is useful for tool handles and furniture.  Some of the species in the genus are evergreen, but most of the North American species shed their leaves in the fall.  The fruit, commonly known as an acorn, consists of a detachable nut that is grown under an inverted  cup.

Oaks of the Pacific Coast region. Deer Oak (Quercus sadleriana) a small shrub of northwestern California and southwestern Oregon is not mentioned in Miller and Lamb and is not pictured here. Leather Oak (Quercus durata) also found in California, is also not pictured.

Oak and Beech Family (Fagaceae) has about 600 species usually  divided into about six different genera. The most common genus in North America is the Oak (Quercus) genus. This is a large and important genus that contains many valuable species of trees. To facilitate study of Quercus, the Oak and Beech Family have been divided into several different sections as follows:

        Non Oak Group  (N. American)       (Beeches, etc)
        Red Oaks of Eastern USA
        White Oaks of Eastern USA
        Oaks of West Texas
        Oaks of SW USA  (Arizona, New Mexico, Colorado, etc)
        Oaks of Pacific Coast region   (California, Oregon, etc.)
        Eurasian Species of Oaks and Chestnuts


The following is a table of the Oak species of the United States:

Oak (Quercus) Miller and Lamb's book, Oaks of North America,  published in l985, was used to develop a preliminary list of the oak (Quercus) species found in the United States. This list was modified by comparing it to A California Flora by Philip Munz and Arizona Flora by Kearney and Peebles. (* means that this species is discussed and pictured)

Oaks of Eastern United States (43 species)

Species                Common Name        Location      
 *Quercus acutissima   Sawtooth           Asia - Int. SE USA
 *Quercus alba         White              WI, TX, NY, GA
  Quercus arkansana    Arkansas           Local-AR and AL
 *Quercus bicolor      Swamp White        PA to MO
 *Quercus chapmanii    Chapman            FL
 *Quercus coccinea     Scarlet            CT to AL
  Quercus durandi      Durand             Local: TX to NC
  Quer d. breviloba    Bigelow            TX and Ok
 *Quer ellipsoidalis   N. Pine            WI etc.
 *Quercus falcata      S. Red             VA to La.
 *Quer f. pagodifolia  Cherrybark         Southern Forests
  Quercus georgiana    Georgia            Local, Ga and SC
  Quercus ilicifolia   Bear               MA, PA, etc.
 *Quercus imbricaria   Shingle             MO to OH
  Quercus incana       BlueJack           VA to TX to FL
 *Quercus laurifolia   Laurel             LA to VA to FL  
 *Quercus laevis       Turkey             FL, VA, etc.
 *Quercus lyrata       Overcup            NC to TX
 *Quer marilandica     Blackjack          NJ to TX
 *Quer macrocarpa      Bur                ND, TX, OH, etc
 *Quercus michauxii    Swamp Chestnut     LA to VA
 *Quercus muehlenbergii Chinkapin          TX, AL, OH, IL  
 *Quercus myrtifolia   Myrtle             FL
 *Quercus nigra        Water              NC to TX, etc.
  Quercus nuttalli     Nuttall            LA, AR, & MS
  Quer oglethorpensis  Oglethorpe         Local-GA. and SC
 *Quercus palustris    Pin                OH to MI
 *Quercus phellos      Willow             TX to VA, etc.
 *Quercus prinoides    Dwarf Chinkapin    NY to MI
 *Quercus prinus       Chestnut           TN to PA
  Quercus pumila       Runner             Gulf Coast to VA
 *Quercus robur        English            Europe/Introduced  
  *Quercus rubra       Northern Red       MA to MN to AL
 *Quercus shumardi     Shumard Oak        NC to TX
 *Quercus s. texana    Texas Red          Central TX
 *Quercus stellata     Post               TX, MO, FL, VA
 *Quer s. margaretta   Sand Post          Sandy sites
  Quer s. paludosa     Delta Post         Bottomlands
 *Quercus virginiana   Live               TX, Gulf Coast, FL
  Quercus v.geminata   Sand Live          NC to LA
  Quer v.fusiformis    Texas Live         Central TX
  Quer v.minima        Dwarf Live         NC to TX
 *Quercus velutina     Black              IO to MA to GA

West Texas Oaks (9 less 1 Listed Above)

Species               Common Name        Location
  Quer depressipes     Mexican Dwarf      Local-West TX
  Quercus durandi      Bigelow            Listed Above    
  Quercus glaucoides   Lacey              Local - Cent TX
  Quercus gravesii     Graves             Local-West TX
  Quer graciliformis   Chisos             Local-West TX  
  Quercus hinckleyi    Hinckley           Local-West TX
  Quercus intricata    Coahuila Scrub     Local-West TX
  Quercus pungens      Vasey              Local - West TX
  Quercus tardifolia   Lateleaf           Local-West TX

Southwest Oaks (16)

Species               Common Name        Location
   Quercus arizonica   Arizona White      W.TX to AZ & MX
   Quer chrysolepis    Canyon Live        AZ and CA
   Quercus dunnii      Dunn               AZ and S. CA
   Quercus emoryi      Emory              AZ
  *Quercus gambeli     Gambel             UT and CO
   Quercus grisea      Gray               TX, AZ, & NM      
   Quercus harvardii   Shin               OK, West TX, NM
   Quer hypoleucoides  Silverleaf         Local-MX NM & AZ
   Quercus mohriana    Mohr               West TX
   Quer muehlenbergii  Chinkapin          Local-West TX NM
   Quer oblongifolia   Mexican Blue       Local-MX & AZ
   Quercus pungens     Sandpaper          Local - S.W. USA
   Quercus rugosa      Netleaf            MX to South USA
   Quercus toumeyi     Toumey             Local S. AZ & MX
   Quercus turbinella  Shrub Live         NM, AZ, and CA
   Quercus undulata    Wavyleaf           AZ and NM

Pacific Coast Oaks (16 less 3 listed above)

Species               Common Name         Location
  *Quercus agrifolia   California Live     Coast S and C CA
   Quercus chrysolepis Canyon Live         Listed Above
  *Quercus douglasii   Blue                Central CA
   Quercus dunni*      Dunn                Listed Above
   Quercus durata+     Leather             CA Mountains
  *Quercus dumosa      Calif. Scrub         Coastal S. CA
  *Quercus engelmannii Engleman            Local - S. CA
  *Quercus garryana    Oregon White        N. CA to WA
  *Quercus kelloggii   California Black    N. CA
   Quercus lobata      California White    Central CA
   Quercus macdonaldi  McDonald            Pacific Islands
   Quercus sadleriana  Deer                Local,NW/CA,SW/OR
  *Quercus tomentella  Island Live         Pacific Islands
   Quercus turbinella# Shrub Live          NM, AZ, and CA      
   Quer vaccinifolia^  Huckleberry         N. half CA
  *Quercus wislizenii  Interior Live       Central CA

  
*Dunn Oak (Quercus dunni) is also called by the synonym of Quercus palmeri.
  
+Leather Oak (Quercus durata) is mentioned in Miller and Lamb's  text as a subspecies of Q. dumosa.
  
#Quercus turbinella is listed in Miller and Lamb as a sub of Q. dumosa.

^Huckleberry Oak (Quercus vaccinifolia) from C. California to  Oregon is listed in Miller and Lamb as a sub of Quercus  chrysolepis.

Fagales Order is usually divided into two different families: the birches and the oaks.

Dicots (Dicotyledoneae Class) are the predominant group of vascular plants on earth. With the exception of the grasses (Monocots) and the Conifers (Gymnosperms), most of the larger plants that one encounters are  Dicots. Dicots are characterized by having a seed with two outer shell coverings. Some of the more primitive Dicots are the typical hardwood trees (oaks, birches, hickories, etc). The more advanced Dicots include many of the Composite Family flowers like the  Dandelion, Aster, Thistles, and Sunflowers. Although many Monocots reach a very high degree of specialization, most botanists feel that the Dicots represent the most advanced group of plants.

Seed plants (Phylum Embryophyta) are generally grouped into one large phylum containing three major classes: the Gymnosperms, the Monocots, and the Dicots. (Some scientists separate the Gymnosperms into a separate phylum and refer to the remaining plants as flowering plants or Angiospermae.)

For North American counts of the number of species in each genus and family, the primary reference has been John T. Kartesz, author of A Synonymized Checklist of the Vascular Flora of the United States, Canada, and Greenland (1994). The geographical scope of his lists include, as part of greater North America, Hawaii, Alaska, Greenland, Puerto Rico, and the Virgin Islands.

Kartesz lists 21,757 species of vascular plants comprising the ferns, gymnosperms and flowering plants as being found in greater North America (including Alaska, Hawaii, Greenland, Puerto Rico and the Virgin Islands).

There are estimates within the scientific world that about half of the listed North American seed plants were originally native with the balance being comprised of Eurasian and tropical plants that have become established.

Plant kingdom contains a large variety of different organisms including mosses, ferns, and seed plants. Most plants manufacture their energy from sunlight and water. Identification of many species is difficult in that most individual plants have characteristics that have variables based on soil moisture, soil chemistry, and sunlight.

Because of the difficulty in learning and identifying different plant groups, specialists have emerged that study only a limited group of plants. These specialists revise the taxonomy and give us detailed descriptions and ranges of the various species.  Their results are published in technical journals and written with highly specialized words that apply to a specific group.

On the other hand, there are the nature publishers. These people and companies undertake the challenging task of trying to provide easy to use pictures and descriptions to identify those species.