. Annual report of the Board of Regents of the Smithsonian Institution. Smithsonian Institution; Smithsonian Institution. Archives; Discoveries in science. 376 ANNUAL EEPOET SMITHSONIAN INSTITUTION, 1907. II. Equisetales. The Paleozoic Equisetales, often made into a class of their own, under the name Calamariales or Calamariacese, were one of the domi- nant groups of plants at that period, attaining the stature of large trees, which appear to have formed an important constituent of the Carboniferous forests. Hence their organization was in various re- spects on a higher level than that of thei
. Annual report of the Board of Regents of the Smithsonian Institution. Smithsonian Institution; Smithsonian Institution. Archives; Discoveries in science. 376 ANNUAL EEPOET SMITHSONIAN INSTITUTION, 1907. II. Equisetales. The Paleozoic Equisetales, often made into a class of their own, under the name Calamariales or Calamariacese, were one of the domi- nant groups of plants at that period, attaining the stature of large trees, which appear to have formed an important constituent of the Carboniferous forests. Hence their organization was in various re- spects on a higher level than that of their recent survivors, repre- sented by the genus Equisetum; at the same time, allowing for these Fig. 2.—Cheirostrohus Pettycurensis. Diagram of cone, the upper part in transverse, the lower in radial section. In the transverse section, sis sporophylls, each showing three segments, are represented. 8p. a., section in plane of sterile segments ; Sp. b., section in plane of sporangiophores; st, lamina; of sterile segments ; /, laminae of sporangio- phores; sin, sporangia ; ;•. h., vascular hundles supplying sporophylls; Ax, axis; cy, stele. The longitudinal section shows the sporangiophores and sterile segments in their relation as ventral and dorsal lobes of the sporophylls; lettering as before. adaptive differences, the structure of the Calamariaceae had very much in common with that of our familiar Equisetaceas. Even in habit there seems to have been a considerable resemblance to recent forms. The leaves were always in whorls, and usually of simple form and comparatively small size, though not so reduced as in Equisetum itself. In the oldest known Calamarian, however, the Devonian and Lower Carboniferous genus Archreocalamites, the leaves were often dichotomously compound, thus showing an inter-. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations
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