The American Rose Annual, 27: 11-15 (1942)
Very Ancient Roses
Charles E. Resser,
Curator of Stratigraphic Paleontology,
U.S. National Museum, Washington, D.C.*

EDITOR'S NOTE.—At the Washington annual meeting of the American Rose Society on September 19, there was given to a fascinated audience in the National Museum this presentation of the roses of thirty-five million years ago. It was illustrated by lantern slides of the fossil leaves and stems discussed by Dr. Resser, who has kindly also provided not only the picture evidence to be seen facing page 7, but the scholarly abstract which here follows.

To thus be provided with evidence that roses were blooming in America thirty-five million years ago is surely impressive, as also is Dr. Resser's concluding sentence that "When man arrived on the earth, there was the beauty and fragrance of the rose to make his home most enjoyable."

FOSSILS OF AMERICAN ROSES GROWING THIRTY-FIVE MILLION YEARS AGO
Fig. 1. Rosa Wilmattae Cockerell
Figs. 2-4. Stem and leaves from Crooked River, Ore.
Fig. 5. Rosa Hillae Lesquereux
Fig. 6. Rosa (?) inquirenda Knowlton
Fig. 7. Rosa sp.
Fig. 8. Rosa Scudderi Knowlton
Figs. 1, 5, 6, 8 are from Florissant, Colo.; Fig. 7 is from Crooked River, Ore.

FOSSIL ROSES from the United States are very rare, authentic specimens having been found at only two localities, both in rocks of Oligocene age. These localities are Florissant, Colo., and on Bridge Creek and Crooked River in central Oregon. The fossils consist of impressions of leaves, a fruit, a supposed bud, and a portion of a stem with thorns.

Dr. Roland W. Brown, Paleobotanist of the U. S. Geological Survey, furnished the information for this paper. He studied both areas thoroughly and collected some of the best specimens himself. During the field season of 1941 he collected a fine lot of fossils in central Oregon, securing excellent representatives of maples — leaves, wood, and seeds — fossil beans still in the pod, and other plants, among which are several thorns and a stem that belong either to a rose or to a raspberry, usually one of the closest associates of the wild rose today. [12]

In the first place it is necessary to remember that roses today require only average moisture supplies, and hence avoid the really wet places. No doubt their early ancestors had the same habit. If so, this accounts in part at least for their scarcity as fossils, for they did not grow in swampy places nor in the flood plains of streams where the ground became muddy. Plants growing in drier ground and away from the supply of muds that can bring about quick burial before decay sets in, have less chance for their leaves, stems, and fruits to leave a fossil record. If these assumptions of the habitat of ancient roses should be true, it is apparent that some special conditions must have obtained to trap their remains in the sediments so that a record could come down to us. This is precisely what did happen in the case of the two occurrences of fossil roses, because in each case volcanic eruptions furnished vast supplies of dust, and of mud when the dust was mixed with rain, so that both the plants and animals of that day were quickly overwhelmed and buried away from an oxygen supply and bacterial activity that would have rotted their remains in a brief time. Thus we may explain the rarity of fossil roses, and their absence from intervening strata, simply by the fact that such fortuitous circumstances did not give us other records. Of course, not all fossil plant localities have yet been discovered, nor have all collections on hand in the various museums of the world been studied; consequently we do not know but that additional specimens may turn up any day, either in rocks of Oligocene or even pre-Oligocene age, or from younger beds deposited after Oligocene time; that is, between that period and the present. The few specimens from Oligocene and Miocene strata in Europe are of somewhat doubtful identification, and so do not change the picture.

Florissant is a small village in South Park, at an elevation of 8,193 feet above sea-level, 35 miles west of Colorado Springs, with Pike's Peak halfway between. The fossils are preserved in a reddish shale that was once mud and volcanic ash, deposited in late Oligocene time is an intermontane lake basin, about twelve miles long and three miles wide. Not much of this shale deposit remains, because erosion has been extensive, both by nature and by man, for man, who has exploited nearly every [13] available outcrop, has collected specimens that have gone into museums and private collections in all parts of the world.

The compound leaves from Florissant include a 3-leaved specimen named Rosa Hillae Lesquereux, a 5-leaved specimen named R. Willmattae Cockerell, and a 7-leaved specimen called R. Scudderi Knowlton. It is quite likely that these three nominal species are only a single species, perhaps comparable to the living R. nutkana Presl, which ranges from Alaska to Oregon and Utah.

The fruit appears as a thick central mass surmounted by five calyx lobes. It is called R. (?) inquirenda Knowlton.

The Florissant roses are associated with the remains of juniper, pine, sequoia, hickory, barberry, poplar, willow, alder, ironwood, oak, elm, redbud, locust, hydrangea, hawthorn, mountain mahogany, cedrela, ailanthus, sumac, maple, soap-berry, ash, and many others--an assemblage probably not duplicated exactly anywhere in the world today. Most of these species resemble those growing in regions and at altitudes where the annual rainfall averages 25 inches or less. It is judged, therefore, that this association was an upland one, but not as high as the present elevation of the fossil beds, because there is evidence from the structure of these and adjacent strata that mountain-making movements occurred in in that part of the Rockies subsequent to the deposition of the fossil beds. Inasmuch as only suggestive comparisons can be made between fossil and living species, it is always risky to draw too clear a picture of the climatic and ecological setting of a fossil flora. Therefore, although it would seem at first glance that the fossil flora from Florissant existed under somewhat moister and warmer conditions than those obtaining in the region today, it may be that there was merely a better annual distribution of moisture and temperature conditions in that area during Oligocene time.

Bridge Creek and Crooked River in central Oregon drain a region in which fossiliferous shales crop out at a general elevation of 2,800 feet. These shales carry fossil plants and are somewhat similar in appearance to those from Florissant. They were probably deposited at about the same time.

The roses from these shales consist of leaves and a portion of [14] a stem with thorns. The best specimen is 7-leaved, and was collected on Bridge Creek at a locality 9 miles northwest of Mitchell by Dr. Roland W. Brown, in 1938. The stem comes from a locality near Post in the Crooked River Basin. These specimens are thought to represent the same species as those from Florissant.

Associated with these roses are pine, fir, sequoia, willow, ironwood, hornbean, alder, beech, chestnut, oak, elm, barberry, sycamore, service-berry, hawthorn, cherry, redbud, yellow-wood, cedrela, maple, ceanothus, linden, dogwood, madrone, katsura, and others. Judging from this association the climatic conditions at that time were much more favorable for plant life than those prevailing in the region today. The situation may have been comparable to that today in the Appalachians of Virginia, North Carolina, and Kentucky, or to portions of the Coast Ranges of California and Oregon.

It will have been noted that two species, namely ailanthus at Florissant, and katsura (Cercidiphyllum) at Bridge Creek, are representatives of genera not native (although introduced) to the United States today, but belong to the flora of eastern Asia. A long list could be drawn up to emphasize this fact of a once close relationship between the floras of the western United States and those of eastern Asia. Changes in physical and climatic conditions, however, disrupted this affinity, probably during the Pliocene epoch. It is possible, therefore, that the species of fossil roses here discussed may be more closely related to some species now existing in Asia than to any living in this hemisphere. Geologists do not measure time in years, but the public usually desires some estimate in the more familiar units.

After Becquerel found out the existence of invisible rays in 1896, Mme. Curie followed with epoch-making discoveries concerning radioactive elements. Today we know of fourteen naturally radioactive elements which are derived in succession from uranium, and others from thorium and a third source. Atoms of helium are lost from the atoms of the radioactive elements which causes definite transformations in a line of descent at a determinable time rate. Geologists have taken these facts, and wherever it is possible to obtain suitable rocks with radio- [15] active ingredients, have calculated the age of the containing beds in terms of years. From these we derive the following approximate ages. It must be remembered, however, that while these figures are rather definite as to relative ages, their absolute values may not be finally determined.

Immediately preceding the recent is the Pleistocene period, the great ice age. Before that comes the Pliocene epoch, and earlier still the Miocene. The Oligocene, Eocene, and Cretaceous epochs follow in turn as we look backward in time. Analyses of rocks with radioactive minerals place the early Pliocene time about 13 million years ago, the Miocene 18 million, and the upper part of the Oligocene from 32 to 34 million years. The next older figure available is 70 million years for the latter part of the Cretaceous epoch.

Roses, then, are truly a long-lived plant, having been on the earth at least 35 million years. It would be gratifying — and perhaps some day someone will find the fossils — to have a more complete record of roses. It is altogether possible that we might find fossil roses in beds below the Oligocene, for the associated plants were in existence for long ages prior to the deposition of the Florissant beds. Sometime nature may reveal that roses were trapped in sediments laid down between the Oligocene and the recent. Of one thing we may be sure: When man arrived on the earth, there was the beauty and fragrance of the rose to make his home most enjoyable.