ERYTHEA A JOURNAL OF BOTANY, WEST AMERICAN EDITED BY WILLIS LINN JEPSON AND OTHERS, OF THE DEPARTMENT OF BOTANY, UNIVERSITY OF CALIFORNIA. VOLUME I. BERKELEY, CALIFORNIA. 1893. 17747 CUBERY & COMPANY, PRINTERS 77 THE VEGETATION OF THE SUMMIT OF MOUNT HAMILTON. By EDWARD L. GREENE. A number of years ago, even before the Lick Observatory had been completed, Professor Holden, at that time President of the University, expressed to me his desire that, at the earliest convenient time, a botanical survey of Mount Hamilton should be made, and a catalogue of its vegetation. published. From two different points of view, statistics of the spontaneous vegetation of this locality would both be interesting at the time of their publication, and become more so with succeeding years, and the changes incident to the continued occupation of the summit by men and domestic animals. In western California, at least in the middle sections of the State, the original vegetation, free from admixture of foreign elements, can not be found elsewhere but in the midst of the few remaining unbroken tracts of seaboard forest, and on the summits of our higher coast mountains. The mountain tops are the last places to be reclaimed by man from their natural condition, and consequently are the last places to be invaded by those Old World field and wayside and garden weeds which everywhere closely attend the steps of the farmer and horticulturist. One finds the mountain summits tenanted almost solely by their own native plants, long after the valleys and the cultivated lower slopes have had theirs either mixed up with, or more or less nearly exterminated by, the more hardy and aggressive alien growths. It was therefore in Director Holden's mind that our researches upon the mountain vegetation should have been made at the first occupancy of the summit by the astronomers, thus presumably in advance of the arrival of any plant immigrants. It could not then be done; for none unacquainted with California. botany could take even the preliminary steps; and a pressure ERYTHEA. Vol. I, No. 4 [1 April, 1893]. pre of other work at Berkeley which could not be deferred cluded the possibility of its being undertaken by the present writer until the year 1891. However, the date of the completion of the Observatory, and of the consequent occupancy of the station by residents, would certainly have been found too late for the recording of the earliest arrivals in the line of immigrant plants. Some of these must have come perhaps ten years earlier, along with the workmen and their teams, when the foundations of the Observatory were being prepared and the roads made. This earliest work must have involved the importation of provisions, grain and hay to the mountain top, while at the same time the digging and grading prepared places of germination for such seeds of alien plants as thus found their way to the locality. In the second place, Mount Hamilton having been chosen as the site of the Lick Observatory on account of its being a fair weather mountain, as compared with other middle Californian summits of equal or nearly equal elevation, it must be interesting to note how well the native vegetation, as compared with that of the other summits referred to, would have indicated to the botanist without other data, the relative immunity of this mountain top from fogs and long continued rains. The subjoined catalogue, embracing about two hundred and ten species of phanerogramic growths, besides several ferns, is not likely to prove a complete list for the limited and not very definitely circumscribed area which it is meant to cover. It is drawn chiefly from field notes made by the writer during the last week of July, 1891; that is to say, in the midst of the dry season of the year, at a time when the greater proportion of annual species-and these form the great bulk of the native vegetation in all parts of Californiawere long past flowering and quite dead. Owing to this circumstance, no doubt a considerable number of species must have escaped notice entirely; and some of those accredited were seen only in the herbarium of Miss Mildred Holden, as having been collected by her in June. Some others were enumerated out of a small collection brought to me by Mr. C. T. Blake of Berkeley, a botanical amateur of keen eye who does more or less good service in botany whereever he goes on a vacation tour. As to the ground intended to be covered by the catalogue, I may say that it begins at no very precisely marked point, but in a general way embraces the land lying above the line of the Aquarius Road on the north side, and descends to about the same elevation on the southward slope, extending eastward to the Joaquin Murrieta Springs. The relative aridity of Mount Hamilton as compared with such mountains as Diablo and St. Helena, is indicated by the absence of everything which can be called a forest. Such oaks and pines as are of arborescent dimensions are too much scattered to constitute even a grove anywhere, and represent those species only which belong to the dry districts. The Coast Range oaks which, under more favorable conditions become large trees, are here found on the north side only, and near the summit, forming low thickets not much exceeding a man's height. The genus Ceanothus, which in other and less arid mountain districts both of the Coast Range and the Sierra Nevada, often makes up a great proportion of the dense brushwood that covers the slopes and even the lower summits, seems to be wholly absent from Mount Hamilton; and even the Buckthorn is found to be the Rhamnus tomentella of the dry interior of the State, and not the R. Californica of the moist seaboard hills and mountains. Equally strong botanical evidence of a dry atmosphere is found in the abundant development of the genus Eriogonum, the species of which are most numerous in the very dry region of the Great Basin east of the Sierras, few in the Californian Coast Range, and of a somewhat surprising number on the higher slopes of Mount Hamilton, where most of the species are representatives of more southerly districts, and have here, at least in some cases, their northern limit of distribution. Although, as above noted, our list is not like to prove a complete one, it is fairly representative of the flora of this |