Word Study
calamite
CIDE DICTIONARY
calamite, n. [L. calamus a reed: cf. F. calamite.].
A fossil plant of the coal formation, having the general form of plants of the modern Equiseta (the Horsetail or Scouring Rush family) but sometimes attaining the height of trees, and having the stem more or less woody within. See Acrogen, and Asterophyllite. [1913 Webster]
For further exploring for "calamite" in Webster Dictionary Online