M. Adolphe Brongniart has given the following classification of fossil plants, in his Essay "Sur la Classification et la Distribution de Végétaux Fossiles" inserted in the "Mémoires du Muséum d'Histoire Naturelle;" and also printed separately in quarto, Paris, 1822:—
STEMS.
Class I.—Stems whose internal organization is recognisable.
1. Exogenites.—Wood formed of regular concentric layers.
2. Endogenites.—Wood composed of insulated bundles of vessels, which are more numerous
towards the circumference than at the centre.
Class II.—Stems whose internal organization is no longer distinct, but which are characterised by their external form.
3. Culmites.—Stem jointed, smooth; a single impression at each articulation.[94]
4. Calamites.—Stem jointed, regularly striated; impressions rounded, small, numerous,
forming a ring round each articulation, or sometimes wanting.[95]
5. Syringodendron.—Stem channelled, not jointed; impressions dot-like or linear,
arranged in quincunx.[96]