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ON THE CLASSIFICATION OP PLANTS. 7

Classes XII. and XIII.—ICOSANDRIA and POLYANDRIA.

1 le twelfth and thirteenth classes are composed of flowers furnishedwith upwards of twenty stamens. Linnaeus divided these classes; butbotanists have thrown them both into one, and certainly with pro-priety ; the difference being only on the insertion of the stamens. Thetwelfth class (Icosandria) has them inserted into the leaves of theca! 5 r x; but in the other (Polyandria) they are situated on the receptacle.

miy be also remarked, that most of our fruits are of the class Ico-sandria : the small part we call the eye of an apple is nothing but the°alyx fixed, and remaining on the top of the germ till it comes tomaturity.

Class XIV.—DIDYNAMIA.The fourteenth class is composed of plants having flowers bearingfour stamens, two long and two short.—We have mentioned the cha-racter of this class in speaking of (the fourth, where the stamens are ofequal length. In the present class the flowers are of a particularstructure, as the corolla is of that form which is called « gaping"(nvgens). This is seen in the Mint {Mentha).

Class XV. — TETRADYN AMI A.The plants of this have flowers with six stamens, four of which arelonger than the other two : and it thus differs from the plants of thesixth class, in which the stamens of the flowers are all of equal length:from this circumstance the class derives its name, signifying four su-periors. In addition to this essential character, the plants are easily^cognised by their peculiar form. The flower is succeeded by a podmore or less long. For a further description of this, see it in theObdkhs, where it is more fully described.

Class XVI.—MONADELPHIA.2 Slxte enth class is composed of plants the stamens of whoseflowers are all united so as to form one single set. These are in gene-ral placed on the pistil, which forms a kind of pyramid in the centre.The Mallow and H o) | yhock are instances of this.