432. Linnæus seized on the variations in the number of the stamens, as a means of classing the vegetable kingdom into twenty-four denominations.

Those flowers having but one stamen, he called mon-andria; those of two stamens he called diandria; three, tri-andria; so on up to twenty stamens, and above twenty, poly-andria.

When he found stamens, in one flower, and pistils in another, on the same plant, he called them monacia; and on different plants, diœcia, When altogether invisible, cryptogamia.

433. Nothing can be more easy than to remember the names of these 24 classes; they are, 1. Monandria, one stamen.

2. Diandria, two stamens.
3. Triandria, three stamens.

4. Tetrandria, four stamens, equal in length.
5. Pentandria, five stamens.

6. Hexandria, six stamens, all of equal length, 7. Heptandria, seven stamens.

8. Octandria, eight stamens.

9. Enneandria, nine stamens.

10. Decandria, ten stamens, filaments separate. 11. Dodecandria, twelve stamens to nineteen, inserted on the receptacle.

12. Icosandria, twenty or more stamens, inserted upon the calyx or corolla.

13. Polyandria, many stamens, inserted on the receptacle.

14. Didynamia, four stamens, two long, two short.

15. Tetradynamia, six stamens, four long, twe short.

16. Monadelphia, filaments united at bottom, but separate at top.

17. Diadelphia, filaments united in two sets. 18. Polyadelphia, filaments united in three or

more sets.

19. Syngenesia, five stamens united above in the form of a cylinder.

20. Gynandria, stamens inserted on the pistil, or on a pillar elevating the pistil.

21. Monacia, stamens and pistils in separate corollas, upon the same plant.

22. Diacia, stamens and pistils in distinct corollas, upon different plants.

23. Polygamia, various situations; stamens only, or pistils only on one plant, and stamens and pistils on another plant.

24. Cryptogamia, stamens and pistils inconspicuous.

Obs. I have introduced beneath, a representation of the pistils and stamens of a few of the first classes; and the pupil will, doubtless, be led to observe them within any flowers which may fall in his way.

YUNU

1. 2. 3. . 4.

5.

434. The class Triandria 'contains chiefly the natural tribe of grasses; Hexandria the lillies. The Icosandria contains the edible fruit; Polyandria, has many poisonous plants.

The Tetradynamia contains the natural tribe of flowers, which are antiscorbutic.

The Monadelphia is composed chiefly of the mallow tribe.

Diadelphia consists of the pea-tribe, which produce edible seeds.

:

Syngenesia possesses the compound flowers. And the Cryptogamia contains the natural tribes of ferns, mosses, sea-weeds, and mushrooms. Obs.-The first order of the fourteenth class, denominated "Didynamia Gymnospermia" are all innocent or wholesome those of the other order, are fœtid, narcotic, and dangerous; being allied to a large part of the Pentandria Monogynia, known to be poisonous, as containing henbane, night-shade, and tobacco. The whole class Tetradynamia is wholesome. Whenever the stamens are found to grow out of the calyx, they indicate the pulpy fruits of such plants to be wholesome. The papilionaceous plants are wholesome, except the seeds of the laburnum; which, if eaten unripe, are violently emetic and dangerous. Milky plants are generally to be suspected. Umbelliferous plants, which grow in dry or elevated situations, are aromatic, safe, and often wholesome; while those that inhabit low and watery places, are among the most deadly poisons.

435. Other distinctions in each class produce a division of the classes, called Orders. A further division of the orders, founded on distinctions in the flower and fruit, lead to the Genera.

Other divisions of the genera, in regard to the root, trunk, leaves, &c. lead to Species: and casual differences in species are called Varieties.

436. The useful substances found in vegetables are, sugar in the sugar-cane, beet, carrots, &c.; gum, or mucilage, which oozes from many trees; jelly, procured from many fruits; bitters, from hops and quassia; and the narcotic principle from the milk of poppies, lettuce, &c.

437. The vegetables of the greatest value to man, are those which produce gluten and starch; as wheat, potatoes, barley, beans, &c. Oils are

produced by pressing the seeds or kernels of vegetables; as olives, almonds, linseed, &c. Volatile oils are distilled from peppermint, lavender, &c. Wax is collected from all flowers by bees.

438. Resins exude like gum from furs and other trees; and are known as balsams, varnishes, turpentine, tar, pitch, &c. Of this class, too, is Indian rubber; which exudes from certain trees in South America.

Iron mixes with the substance of most vegetables; and is the cause of the beautiful colours of flowers. Pot-ash is obtained from the ashes of burnt vegetables.

Obs.-The classes Monæcia and Diœcia, containing the pistil and stamens in different flowers, have the pistil fructified by the bees and other insects, which enter the corolla to extract the honey from the nectarium. The pollen in those flowers which have stamens only, falls on their bodies, and is carried by them to the flowers which have pistils only. And here the wisdom of the Divine Architect of nature is conspicuous, that when the pistil is shorter than the stamens, the flowers grow upright, that the pollen may fall from the anthers of the stamens on the stigma of the pistils; but when the pistil is longer than the stamen, the flower hangs downward, that the pollen, in falling, may be received by the stigma of the pistil.