This lifeform is generally found west of the Continental Divide in North America

Water Birch (Betula occidentalis) is found in the Rocky Mountain area of North America. This Birch rarely exceeds 20 feet in height. The bark is dark and generally does not peel off.

Betula genus (Birches) is a genus of the northern hemisphere with about 50 to 60 species known worldwide.  Kartesz lists 15 species, 16 hybrids, and 19 subspecies as being found in greater North America, including the United States, Canada, Hawaii, Greenland, Puerto Rico and the U.S. Virgin Islands.  Several of the tree species have unusual peeling bark that makes them nice ornamentals.  Birch leaves can be of various shapes, but they generally are toothed.   European white birch (Betula pendula) is considered established in North America.

Birch Family (Betulaceae) contains about 100 different species  usually organized into six different genera. Five of the birch genera are found in the United States. Because of the great interest in this family, included here is a list of the various trees in the Birch family now found the United States and Canada:

  *Alnus glutinosa            European Alder  Introduced USA
   Alnus incana (=tenuifolia) Thinleaf Alder  NW USA
   Alnus incana (ssp rugosa)  Speckled Alder  East N. America
   Alnus maritima             Seaside Alder   Local in USA
   Alnus nepalensis
   Alnus oblongifolia         Arizona Alder   Mexico to Ariz.
   Alnus rhombifolia          White Alder     Pacific NW
  *Alnus rubra                Red Alder       Cal Coast to Alaska
   Alnus serrulata            Tag Alder       SE USA
   Alnus viridis (=sinuata)   Sitka Alder     Pac. NW to Alaska
   Alnus viridis ssp crispa   Green Alder     SE USA
  
   Betula alba                European Birch    Eur. & Int. USA
  *Betula alleghaniensis(lutea)Yellow Birch     E. N. America
   Betula borealis            Northern Birch    NE N. America
   Betula caerulea-grandis    Blue Leaf         E. Canada
   Betula eastwoodiae         Yukon Birch       W. Canada
 * Betula lenta               Sweet, Cherry B
   Betula minor               Minor Birch       Arctic
   Betula murrayana
  *Betula nana(=michauxii, glandulosa) Dwarf   Northern N. Amer.
   Betula neoalaskana
  *Betula nigra               River Birch        E. USA
  *Betula occidentalis        Water Birch        West Mountains
  *Betula papyrifera          Paper Birch        North N. America
  *Betula pendula             Weeping Birch      Eur. & Int. USA
  *Betula platyphylla
  *Betula populifolia         Gray Birch         E.Canada  N.Eng.
  *Betula pubescens           Silver Birch       Eurasia(?)
  *Betula pumila              Swamp Birch        Bogs, widespread
   Betula rotundifolia        Ground Birch       Alaska
   Betula uber                Virginia Birch     Local

   Carpinus betulus           European Hornbeam  Eur. & Int. USA
   Caprinus caroliniana       American Hornbeam  East USA
   Corylus americana          American Hazel     E. N. America
   Corylus avellana           Corkscrew Hazel    Eur. & Int. USA
   Corylus cornuta(=rostrata) Beaked Hazel       E. N. America
   Corylus cornuta ssp calif  California Hazel   West Coast
   Corylus heterophylla
   Corylus maxima             Giant Filbert      Eur. & Int. USA
   Ostrya knowlontonii        Knowlton Hophornbeam Local West USA
   Ostrya virginiana          E. Hophornbeam     E. USA

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.