The Devonian flora seems to have been introduced in the northern parts of the American continent at a time of warm and equable climate, and of elevation of new land out of the Silurian sea. It spread itself to the southward, and was finally destroyed in the great subsidences and disturbances which closed the Devonian age, and which were probably accompanied with refrigeration of climate. It was succeeded by the more massive and richer, but more monotonous flora of the Carboniferous, a period in which large areas of our continents were in the state of swampy and often submerged flats, and in which the climate was again warm and uniform.
Fig. 95.—Asterophyllites parvula (Dn.), and Sphenophyllum antiquum (Dn.). Middle Devonian, New Brunswick.
The Carboniferous age was, even more emphatically than the Devonian, an age of Acrogens and Conifers. A few Carboniferous Fungi have recently been discovered, but there are no known Lichens or Mosses. There seem to be a few Endogens, but no true Exogens. The great bulk of the plants consists of Acrogens and Gymnosperms, as in the previous period. As this flora is so very important and so much better known than any other of those belonging to the infancy of the vegetable kingdom, we may notice a little in detail some of its leading forms.
Fig. 96.—Calamites. Carboniferous.
A, C. Suckovii. B, C. Cistii (Bt.). C, Base of Calamites. D, E, Structures.
From Acadian Geology.