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Trees of Yosemite (1932, 1948) by Mary Curry Tresidder

The Classification of Trees

Botanists make use of various sets of characteristics to trace relationships among plants; the most fundamental one for that purpose seems to be the method of reproduction. The chart entitled “Trees of Yosemite Classified by Families” gives the broad divisions of that part of the plant world with which we are dealing here, placing the trees in families.

Under the family, in turn, is the genus, which is subdivided into species; and it is from the latter two classifications that our plants take their botanical names for scientific use.

These names are necessary for accuracy, as, with the carelessness of popular usage, the same tree may go under different names in different places; the Canyon Live Oak, for instance, Quercus chrysolepis, has a dozen different names in as many places. On the other hand, the same name may be applied to an entirely different tree, on the basis of some superficial resemblance; thus our tamarack, a pine, is of a different genus from the tamarack of the Eastern states, which is a larch, a deciduous tree, though a cone-bearer. Douglas Fir is one of the most confusing of these cases, since it possesses attributes of three genera—the fir, the spruce, and the hemlock—while its lumber goes under the trade name of “Oregon Pine.”

To avoid these pitfalls, the botanist employs a scientific terminology which gives a tree a standard name throughout the world. Thus the botanical name of the Ponderosa Pine (Western Yellow Pine), Pinus ponderosa Dougl., is made up as follows: first, the genus, or kind, which is Pinus, pine, often indicated merely by the initial; then the species of that kind, ponderosa; the third part is the name of the botanist who first assigned it to its proper place in the hierarchy of plants and published his findings. This name is often abbreviated. The species name is sometimes descriptive of characteristics or habitat, as with P. albicaulis, White-Bark Pine; sometimes it, too, is derived from the name of a person, as with P. lambertiana, the Sugar Pine, named by David Douglas in honor of a friend.

Occasionally there is a further segregation beyond the species; the latter may have two or more varieties. This is indicated by the abbreviation “var.” after the species name, followed by the name of the botanist who described it as a variation. Usually it is a form differing as a result of climatic conditions, but it sometimes requires study to determine whether it is a variety or a different species. This is the case with the Jeffrey Pine, considered by some botanists a variety of Yellow Pine, by others as an independent species.

Trees of Yosemite Classified by Families






(Plants with
naked seeds)


(Plants with
covered seeds)

Polycotyledons—having two or
    more seed leaves

   Pine Family (Pinaceae)
     Pines (Pinus)
       Sugar Pine
       Western White Pine
       White-Bark Pine
       Ponderosa Pine
       Jeffrey Pine
       Digger Pine
       Lodgepole Pine
     Hemlock (Tsuga)
       Mountain Hemlock
     False Hemlock (Pseudotsuga)
       Douglas Fir
     Firs (Abies)
       White Fir
       Red Fir
   Redwood Family (Taxodiaceae)
     Giant Sequoia (Sequoia
   Cypress Family (Cupressaceae)
     Incense Cedar
     Sierra Juniper

Yew Family (Taxaceae)
   California Nutmeg

Dicotyledons—having two
    seed leaves only

Birch Family (Betulaceae)
   White Alder
Oak Family (Fagaceae)
   California Black Oak
   Canyon Live Oak
Dogwood Family
   Nuttall Dogwood
Willow Family (Salicaceae)
   Yellow Willow
   Black Cottonwood
   Quaking Aspen
Maple Family (Aceraceae)
   Big-Leaf Maple
Laurel Family (Lauraceae)
   California Laurel

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Online Library: Title Author California Geology History Indians Muir Mountaineering Nature Management