Page:An introduction to physiological and systematical botany (1st edition).djvu/431

 Rh The Orders of the 23d Class, Polygamia, are, according to the beautiful uniformity of plan which runs through this ingenious system, distinguished upon the principles of the Classes immediately preceding.

1. has flowers with Stamens and Pistils on the same plant with others that have only Pistils, or only Stamens; or perhaps all these three kinds of blossoms occur; but whatever the different kinds may be, they are confined to one plant.

2. has the two or three kinds of flowers on two separate plants.

3. has them on three separate plants, of which the Fig is the only real example, and in that the structure of the flowers is alike in all.

The Orders of the 24th Class, Cryptogamia, are professedly natural. They are 4 in Linnæus, but we now reckon 5.

1. . Ferns, whose fructification is obscure, and grows either on the back, summit, or near the base of the leaf, thence denominated a frond. See p. 133.