Text-book of structural and physiological botany . Fig. 540.—Aimidairafertilis. FiG. $^i.—S^heno^hyllnm anmilatttm. Lepidodendra, on the other hand, had much-branched stems,30 or more metres in height, and 4 metrei: in girth, and Palceophytology. 423 were also beautifully marked with scars. Associated withthese were gigantic Equisetaceae known as Calamites^ ofwhich those now existing are as dwarfish representativesas the Lycopodia are of the Sigillariae and existed, however, also in those forests—the trueprimeval forests of the earth—herbaceous plants (Ferns),such as Aiimdar
Text-book of structural and physiological botany . Fig. 540.—Aimidairafertilis. FiG. $^i.—S^heno^hyllnm anmilatttm. Lepidodendra, on the other hand, had much-branched stems,30 or more metres in height, and 4 metrei: in girth, and Palceophytology. 423 were also beautifully marked with scars. Associated withthese were gigantic Equisetaceae known as Calamites^ ofwhich those now existing are as dwarfish representativesas the Lycopodia are of the Sigillariae and existed, however, also in those forests—the trueprimeval forests of the earth—herbaceous plants (Ferns),such as Aiimdaria, Asterophyllum^ and Speiwphylliim^ aswell as some Monocotyledons, Cycadeae, and Coniferae ; and. Fig. 542.—Neuropteris heterophylla. even the number of species was quite considerable. TheSigillariae, Lepidodendra, Calamites, Asterophyllites, andpossibly also the Tree-ferns, attained in this formation theirmaximum development; in the succeeding one their numberdiminishes. In connection with other plants, and perhapsalso with sea-weeds, they form the vakiable deposits of this form they have undergone sometimes more, some-times less change, no trace of their vegetable structure 424 Strtictiiral and Physiological Botany, often remaining, while the accompanying beds of earthreceive their impressions, and preserve a correct image otthem. It frequently happens, however, that entire stemshave become fossilised (Fig. 534, p. 418), and still show theircellular structure in a wonderfully beautiful manner. Wehave no knowledge of the length of time during which theCarboniferous period lasted; but if it may be estimated fromthe thickness of the deposits of coal, many authorities woul
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