-V T f'V ■*^\ ^r,"^ jj<&'l '■^■^ k-^' r ^ 1 J^i^r^.x;^ i ,.,^ 1 .'^- j"?^, ii">F-/ i a'[D'*'TK -. A*."^ ■KP PHIl:A';fi^^i^ ^ ""jm'' 'i 7 ea ued 1 re SPECIAL ISSUE .:. YOSEMITE NATURE NOTES Price 25 Cents From the collection of the n o Prelinger fi a V xJibrary San Francisco, California 2008 RICHARD G. MILLER Yosemite Nature Notes THE MONTHLY PUBLICATION OF THE YOSEMITE NATURALIST DEPARTMENT AND THE YOSEMITE NATURAL HISTORY ASSOCIATION * " VOL XXVI JANUARY, 1947 NO. 1 Broadleaved Trees of Yosemite National Park By C. FRANK BROCKMAN INTRODUCTION This booklet, designed as a com- otherwise sombre nature of our coni- panion to "Cone-bearing Trees of ferous forests. Furthermore, it will be Yosemite," will aid Park visitors in obvious even to a casual observer the completion of a study of the trees that there is a considerable concen- of this area. Although the forests of tration of broadleaved trees in Yose- Yosemite National Pork are primarily mite Valley which, although but a coniferous (1), one will find a number small part of Yosemite National Park, of broadleaved species which em- is the section most frequented by the body specific interest due to the majority of visitors. Thus, to a large character of their spring floral dis- number of people, the broadleaved play, their form, the odor of their trees attract attention out of propor- foliage, the color of their foliage in tion to their relative abundance in the fall, the nature or color of seeds Yosemite forests. and the manner of seed dispersal, The California black oak, which their habitat, and similar factors, occurs in abundance in the Valley, These things render them conspicu- is of significant importance in this ous, thus serving to highlight the regard, particularly in the fall when (1) Thirty-five species of trees grow naturally in Yosemite National Park. Eighteen, the greater part of this number, are broadleaved. However, while this group is in the majority insofar as number of species is concerned, Yosemite forests are essentially coniferous in type, being dominated by the sixteen species of cone-bearing trees which are found here in much greater abundance. In addition the California torreya (Torreya californica), which possesses needle-like, evergreen foliage but which is not a cone-bearing tree, is native to Yosemite National Park. Because of the similarity of its foliage to that of many conifers a description of that species will be found in the booklet on cone-bearing trees. Attention should also be called to those trees which are not native to the Pork but which were introduced into the area during the pioneer period. Included in this category are the American elm, black locust, sugar maple, and a number of varieties of fruit trees — largely apple. The latter are found principally in three orchards on the Valley floor which were planted during the 60's by James C. Lamon and James M. Hutchings, early settlers in this greg, (See page 30). YOSEMITE NATURE NOTES the acorns are conspicuous features, and when its foliage assumes the rich golds and browns characteristic of the season. Likewise the Pacific dogwood is distinctive, not only in the spring when it is festooned with numerous large white blossoms, but also in the fall when it bears clusters of bright red seeds, and when the foliage takes on a characteristic au- tumnal red. Other species possess outstanding characters of a similar nature which attract their share of visitor interest. The foliage of the California laurel gives off a penetrat- ing, pungent odor when bruised; the holly-like leaves of the canyon live oak rarely fail to attract attention; and the quivering of the long-stem- med leaves of the aspen is a familiar sight in the "high country." Leaf Fall and Autumnal Color of Foliage With few exceptions the broad- leaved trees of Yosemite National Park lose their leaves in the fall. This, and its related phenomena, is the result of the tree's preparation for winter for as the season approaches, deciduous trees must necessarily be ready to withstand its rigors. These preparations are largely to prevent excessive transpiration, since abnor- mal loss of water may result in the death of the tree. They are respon- sible for the vivid fall colors charac- teristic of the foliage of many decidu- ous trees, the annual loss of foliage, and the development of many fea- tures useful in winter identification. During the summer the leaves serve as places of food manufacture. As autumn approaches, practically everything of nutritive value to the tree is gradually transferred to other parts and the leaves soon become mere skeletons, their cells containing only pigments which are of no further use. These pigments are responsible for the fall colors. Leaf fall, most obvious of the de- ciduous tree's preparation for winter, is anticipated weeks before the oc- currence of this event. By midsum- mer a layer of loose cells begins to form across the base of the leaf stem. When complete it extends entirely across the stem at the point where it joins the twig, except for the vascular bundles which must necessarily re- main open to facilitate the transpor- tation of food and moisture. Subse- quently an additional layer of corky cells form under the one previously developed. With the advent of fall, with its rains and frosty nights, small crystals of ice develop between the two cell layers. These exert a prying action which snaps the leaf from the twig. The leaf scar, which would otherwise have remained as an open wound, is protected by the corky cell layer. However, this is but one episode in the tree's preparation for winter. By midsummer the buds, conspicuous on the naked twigs in winter, ore formed. These contain the rudimen- tary foliage or flower parts destined for development in the following summer which are protected by scales, waxes, gums, or hairs. In ad- dition growth is retarded and finally ceases, the recently formed tissues are "hardened," and the bark of the twigs and branches is increased in thickness through the addition of corky tissue. BROADLEAVED TREES OF YOSEMITE NATIONAL PARK Ident-ification of Decidious Trees In Winter Such preparations are responsible for the development of a variety of features by means of which one may readily identify deciduous trees in winter primarily by an examination of the naked twigs. Varying with the species, in a manner similar to the more familiar foliage, flowers, or fruits, one finds buds of distinctive form and protective devices placed in typical positions on the twigs, leaf scars of distinctive size and shape with their vascular bundle scars (from one to many) arranged in spe- cific patterns upon the surface, and stipule scars which are present on the twigs of certain species. In ad- dition one may note the color, taste and odor of the twig, the nature and number of the lenticels in the bark, the color and character of the pith found in the central portion of the twig, and the bark itself. The form of the tree is also of assistance in winter identification. This has many variations, from an upright pattern (as in the case of the Pacific dog- wood) wherein the trunk or central '^Tom drawing by C. frank Brockman 1. WILLOWS. Twigs slender, round in cross section. Leaf scars alternate, U-shaped and narrow, with three bundle scars. Buds sessile {not stalked), small, oblong and with but one exposed bud scale. Pith round in cross section and small. 2. BLACK COTTONWOOD. Twigs moderately stout, slightly angular in cross section. Leaf scars large, alternate, broadly crescent shaped to triangular, with three bundle scars. Buds sessile, elongated, conical, gummy and fragrant, with 6-7 overlapping scales. Pi/h rather unull, somcuhat S-angled in cross section. 5. WHITE ALDER. Tuigs slender, somcubat i-sidcd in cross section. Leaf scars alternate; half round, raised, with three bundle scars. Buds large and stalked, with 2-3 reddish-broun laltafe {not overlapping) scales. YOSEMITE NATURE NOTES axis of the tree is continued through the crown, to a wide-spreading type (as in the California black oak) in which case the trunk divides into sev- eral large limbs. Beauty of Deciduous Trees In Winter The beauty of our deciduous trees in winter should not be overlooked. Even though devoid of foliage at that time the rigors of that season lend a distinctive charm to these trees. This is of particular importance in areas such as Yosemite Valley. Here, after a snow storm, the naked branches of the California black oak are often sheathed with a coating of snow which presents a glistening pattern against the background of a blue Si- erra sky. On such occasions these trees contribute, in no small measure, to the development of a veritable fairyland of exquisite beauty. Plan and Organization of This Publication The descriptions of the broadleaved trees found in Yosemite National Park, as noted on the following pages, are presented in a style de- signed primarily for the layman. In friim draning by C. Irjiik Bruikiiiiiii 4. CALIFORNIA BLACK OAK. Twigs moderate to slender, often fluted. Leaf scars alternate, moder- ate to small in size, half round .;;; AnJeno,, Ymeniitr \1«m7/;« /jjs ^ju-riiil tirr room c\hibil. DIGEST OF THE PURPOSES OF THE YOSEMITE NATURAL HISTORY ASSOCIATION Yosemite National Park, Caliiomia Organized for the purpose of cooperating with the National Park Service by assisting the Natuiahst Department of Yosemite National Park in the development of a broad public understanding of the geology, plant and animal life, history, Indians and related interests in Yosemite National Park and nearby regions. It aids in the development of the Yosemite Museum and library, fosters scientific investigations along lines of greatest popular inter- est, offers books on natural history applicable to this area for sale to the public, and cooperates in the publication of Yosemite Nature Notes $1.00 per year Subscription includes all regular and special numbers. Revenue derived from the activities of the Yosemite Natural History Asso- ciation is devoted entirely to further- ing the progress of research and in- terpretation of significant interests in Yosemite National Park. lORAVINO CO.. FRESNO. CAL.