[24]Witham'sFoss. Veget.p. 31.
[24]Witham'sFoss. Veget.p. 31.
[25]For a more detailed description of the process, see Witham'sFoss. Veget.p. 45.
[25]For a more detailed description of the process, see Witham'sFoss. Veget.p. 45.
[26]The solitary lignite of the Lower Old Red Sandstone, seems to have been araucarian. Miller'sFootprints of the Creator, p. 203.
[26]The solitary lignite of the Lower Old Red Sandstone, seems to have been araucarian. Miller'sFootprints of the Creator, p. 203.
[27]Footprints of the Creator, p. 192.
[27]Footprints of the Creator, p. 192.
These coniferous trees do not appear to occur among the erect stems of the coal-beds, at least they are very rare in such a position. Their more usual appearance is that of drifted, branchless trunks, imbedded along with other fragmentary plants in deep strata of sandstone. They probably grew on higher ground than the swamps which supported the sigillariæ and their allies, and might have been carried down by streams, freighted out to sea, and so deposited among the sediment that was gathering at the bottom.
The remains of cycadaceous plants have been described among the vegetation of the coal-measures; but only fragments have as yet been found. The modernCycadeæare low shrubs or trees, with thick stems of nearly uniform breadth, crowned with a dense clump of spreading fronds which resemble both those of the palms and the ferns. They are natives of the warmer regions of both hemispheres.
So long ago as the year 1835, Dr. Lindley figured a flower-like plant, to which he gave the name ofAntholites, ranking it among theBromeliaceæ, or pine-apple group. It was afterwards suspected by Dr. Hooker to belong rather to the coniferæ; and he supposed that the so-called floweretsmight be really tufts of young unexpanded leaves. An examination of a more perfect specimen, however, has induced that distinguished botanist to alter his convictions and return to the original decision of Lindley, that the antholites are really flowers.[28]InFig. 15, therefore, which represents one of these coal-measure fossils, the reader beholds the oldest flower that has yet been found; and surely it is of no little interest to know, that amid the rank, steaming forests of the Carboniferous era, with all their darkness and gloom, there were at least some flowers—flowers, too, that were allied to still living forms, and breathed out a rich aromatic fragrance.
[28]See Dr. Hooker's remarks in the Supplement to the fifth edition of Lyell's Manual, p. 31.
[28]See Dr. Hooker's remarks in the Supplement to the fifth edition of Lyell's Manual, p. 31.
Fig. 15.—Antholites.
Fig. 15.—Antholites.
In fine, from all the genera and species of plants that have been detected in the strata of the coal-measures, it would appear that the flora of that ancient period was in a high degreeacrogenous—that is to say, consisted in great measure of ferns, club-mosses, and other members of the great group of plants known asacrogens. This word literally meanstop-growers, and is applied to those plants which increase in height, but not in width, since they attain at first nearly their ultimate diameter. Such plants occupy a low position in the botanical scale. Mingled with the numerous genera of carboniferous ferns and club-mosses, we find the remains of a much higher grade of vegetation—that of thegymnogens, or plants that bear naked seeds—such as the firs and pines. There also seem to have been a fewendogenousflowering plants. Viewing, then, this flora on the whole, it presents us with many striking resemblances to certain botanical regions of the present day. Many of the tropicalislands abound in ferns, and contain very few flowering plants. But New Zealand affords perhaps the closest parallel. That island is in certain parts highly mountainous, its loftiest summits being covered with glaciers. The hills throughout large districts are bare, or covered with a scanty herbage, while in other localities they are densely clothed with forests of pine, beech, and other trees. These forests sweep on to the lower grounds, where they are replaced by a thick growth of fern and flax-plant intermingled with dragon-trees and graceful tree-ferns, while the more swampy regions support a rich profusion of reeds and rushes. Such a condition of things affords a close parallel to the probable vegetation of the Carboniferous period—an immense preponderance of ferns and arborescent acrogens, with an intermixture of large coniferous trees. From the general scantiness of a flora where ferns predominate, it has been argued that the swamps of the coal-measures nourished a luxuriant repetition of comparatively few species; and this hypothesis also receives confirmation from the vegetation of New Zealand. Another deduction founded on the resemblance of the ancient to the modern flora, refers to the conditions of heat and moisture. It has been inferred that the climate of the coal period was equable and humid, like that of New Zealand—a supposition much more natural and simple than that, once so much in vogue, of a heated atmosphere densely charged with carbonic acid gas. That the air of the Carboniferous period differed in no material respect from the air of the present day, seems at last proved by the remains of air-breathing animals having been found among the coal-beds; and there seems no reason why the higher mountain-tops of the same epoch may not have been clothed with glaciers as those of New Zealand are. As yet we have no evidence of the fact, but it is by no means beyond the possibility of proof.[29]
[29]See Professor Ramsay's suggestive Memoir on Permian Breccias inQuarterly Journal of the Geological Society, vol. xi. p. 185.
[29]See Professor Ramsay's suggestive Memoir on Permian Breccias inQuarterly Journal of the Geological Society, vol. xi. p. 185.