The Geological History of Plants

by Sir John William Dawson

“Algæ.—A small and delicate form, allied to Chondrites.

“Ferns.—Twelve species, generally similar and in part identical with those described by Heer from the Cretaceous beds of Greenland, and referred to the genera Dicksonia, Gleichenia, and Aspidium.

“Cycads.—Two species, probably identical with the forms from Greenland described by Heer under the names of Podozamites marginatus and P. tenuinervis.

“Conifers.—Fourteen species, belonging to the genera Moriconia, Brachyphyllum, Cunninghamites, Pinus, Sequoia, and others referred by Heer to Juniperus, Libocedrus, Frenelopsis, Thuya, and Dammara. Of these, the most abundant and most interesting are Moriconia cyclotoxon—the most beautiful of conifers—and Cunninghamites elegans, both of which occur in the Cretaceous clays of Aachen, Prussia, and Patoot, Greenland. The Brachyphyllum was a large and strong species, with imbricated cones, eight inches in length.

“The angiosperms form about seventy species, which include three of Magnolia, four of Liriodendron, three or four of Salix, three of Celastrophyllum (of which one is identical with a Greenland species), one Celastrus (also found in Greenland), four or five Aralias, two Sassafras, one Cinnamomum, one Hedera; with leaves that are apparently identical with those described by Heer as belonging to Andromeda, Cissites, Cornus, Dewalquea, Diospyros, Eucalyptus, Ficus, Ilex, Juglans, Laurus, Menispermites, Myrica, Myrsine, Prunus, Rhamnus, and others not yet determined.

“Some of the Aralias had palmately-lobed leaves, nearly a foot in diameter, and two of the tulip-trees (Liriodendron) had leaves quite as large as those of the living species. One of these had deeply lobed leaves, like those of the white oak. Of the other, the leaves resembled those of the recent tulip-tree, but were larger. Both had the peculiar emargination and the nervation of Liriodendron.

“Among the most interesting plants of the collection are fine species of Bauhinia and Hymenæa. Of these, the first is represented by a large number of leaves, some of which are six or seven inches in diameter. They are deeply bilobed, and have the peculiar and characteristic form and nervation of the leaves of this genus. Bauhinia is a leguminous genus allied to Cercis, and now inhabits tropical and warm temperate climates in both hemispheres. Only one species occurs in the United States, Bauhinia lunarioides, Gray, found by Dr. Bigelow on the Rio Grande.

“Hymenæa is another of the leguminosæ, and inhabits tropical America. A species of this genus has been found in the Upper Cretaceous of France, but quite different from the one before us, in which the leaves are much larger, and the leaflets are united in a common petiole, which is winged; this is a modification not found in the living species, and one which brings it nearer to Bauhinia.

“But the most surprising discovery yet made is that of a number of quite large helianthoid flowers, which I have called Palæanthus. These are three to four inches in diameter, and exhibit a scaly involucre, enclosing what much resembles a fleshy receptacle with achenia. From the border of this radiate a number of ray florets, one to two inches in length, which are persistent and must have been scarious, like those of Helichrysum. Though these flowers so much resemble those of the compositæ, we are not yet warranted in asserting that such is certainly their character. In the Jurassic rocks of Europe and India some flowers not very unlike these have been found, which have been named Williamsonia, and referred to cycads by Carruthers. A similar fossil has been found in the Cretaceous rocks of Greenland, and named by Heer Williamsonia cretacea, but he questions the reference of the genus to the Cycadeæ, and agrees with Nathorst in considering all the species of Williamsonia as parasitic flowers, allied to Brugmansia or Rafflesia. The Marquis of Saporta regards them as monocotyledons, similar to Pandanus. More specimens of the flowers now exhibited will perhaps prove—what we can now only regard as probable—that the Compositæ, like the Leguminosæ, Magnoliaceæ, Celastraceæ, and other highly organised plants, formed part of the Cretaceous flora. No composite flowers have before been found in the fossil state, and, as these are among the most complex and specialised forms of florescence, it has been supposed that they belonged only to the recent epoch, where they were the result of a long series of formative changes.”