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


Pine Family

Pine Family The pine family has more representatives in the Yosemite region than has any of the other families, in number of species and in actual number of trees. Botanically it includes not only pines but also firs, hemlock, spruce, and Pseudotsuga. Except when the pine family is specifically mentioned, however, “pine” will be used of the genus, not the family.

Pines have linear leaves, or needles, and bear them in a sheath upon the branch, with from one to five needles in a cluster, the number varying with the species. New clusters form on the young twigs, which push outward each year. The needles may remain on the tree for a time varying with the species from two to six years.*

The woody cones mature the second season. With some pines the cone falls within a few weeks after the ripened seeds have been shed, while with others the cone remains on the tree indefinitely. In the case of a few pines, such as the Knobcone, the seed is so tightly held that it is usually released only by the intense heat of a forest fire.

Sudworth classes the pines merely as white and yellow; Jepson divides the second group into yellow, nut, and closed-cone pines.

Three of our trees belong in the first group, all of which are characterized by bearing five needles in a sheath. The Sugar Pine occurs mainly in the Transition Zone, the Western White Pine in the Canadian, and the White-Bark Pine in the Hudsonian Zone.

Three of our trees are Yellow Pines, in Jepson’s classification: the Ponderosa Pine and the Jeffrey Pine, both of which have three needles in a sheath, and the Lodgepole Pine, which has two comparatively short needles in a bundle. The Digger Pine is a nut pine, and its needles are three in a sheath.

In addition to the seven pines ordinarily seen in the Park, a limited number of members of two other species may possibly be encountered. The Piñon, P. monophylla Torr., or Single-Leaf Pine, which is common on the eastern slope of the Sierra Nevada, has a few representatives of its species in the Park, above the Tuolumne River not far from Hetch Hetchy. The other possible species is the Knobcone Pine, P. attenuata Lemm., mentioned above as belonging to the closed-cone type. Lone individuals have been found in scattered places in the Park; just below El Portal, a little outside the Park boundary, two of these trees may be seen to the north of the highway.

* Sudworth, Forest Trees of the Pacific Slope, page 19.


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