I. Vegetabilia.—Vegetables.

These may be conveniently arranged in four classes, as follows:—

I. Cryptogamia; acotyledonous, asexual, or flowerless: Stem and leaves undistinguishable: 1. Thallogenae.
Stem and leaves distinguishable: 2. Acrogenae.
II. Phanerogamia; sexual, or flowering: Cotyledons solitary or alternate; wood of stem youngest in the centre: 3. Endogenae.
Cotyledons opposite or verticillate; wood of stem youngest at the circumference: 4. Exogenae.

The Elements of Materia Medica and Therapeutics, Vol. II, 3th American ed., was written by Jonathan Pereira in 1854.