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f the highest class of cryptograms, including the ferns, etc. See Cryptogamia. The Age of Acrogens (Geol.), the age of coal plants, or the carboniferous era.

Increasing by growth from the extremity; as, an acrogenous plant.

metimes attaining the height of trees, and having the stem more or less woody within. See Acrogen, and Asterophyllite.

embraces three periods, the Subcarboniferous, the Carboniferous, and Permian. See Age of acrogens, under Acrogen. -- Carboniferous formation (Geol.), the series of rocks (including sandstones, shales, limestones, and conglomerates, with beds of coal) which make up the strata of the Carboniferous age or period. See th…

owers, and reproduced by minute spores of various kinds, or by simple cell division. { 1. Acrogens. -- Plants usually with distinct stems and leaves, existing in two alternate conditions, one of which is nonsexual and sporophoric, the other sexual and oöphoric. Divided into Vascular Acrogens, or Pteridophyta, having t…