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6. The Plant, in its botanical sense, includes every being which has vegetable life, from the loftiest tree which adorns our landscapes, to the humblest moss which grows on its stem, to the mould or fungus which attacks our provisions, or the green scum that floats on our ponds.

7. Every portion of a plant which has a distinct part or function to perform in the operations or phenomena of vegetable life is called an Organ.

8. What constitutes vegetable life, and what are the functions of each organ, belong to Vegetable Physiology ; the microscopical structure of the tissues composing the organs, to Vegetable Anatomy ; the composition of the substances of which they are formed, to Vegetable Chemistry ; under Descriptive and Systematic Botany we have chiefly to consider the forms of organs, that is, their Morphology, in the proper sense of the term, and their general structure so far as it affects classification and specific resemblances and differences. The terms we shall now define belong chiefly to the latter branch of Botany, as being that which is essential for the investigation of the Flora of a country. We shall add, however, a short chapter on Vegetable Anatomy and Physiology, as a general knowledge of both imparts an additional interest to and facilitates the comparison of the characters and affinities of the plants examined.

9. In the more perfect plants, their organs are comprised in the general terms Root, Stem, Leaves, Flowers, and Fruit. Of these the three first, whose function is to assist in the growth of the plant, are Organs of Vegetation ; the flower and fruit, whose office is the formation of the seed, are the Organs of Reproduction.

10. All these organs exist, in one shape or another, at some period of the life of most, if not all, flowering plants, technically called phænogamous or phanerogamous plants ; which all bear some kind of flower and fruit in the botanical sense of the term. In the lower classes, the ferns, mosses, fungi, moulds or mildews, seaweeds, etc., called by botanists cryptogamous plants, the flowers, the fruit, and not unfrequently one or more of the organs of vegetation, are either wanting, or replaced by organs so different as to be hardly capable of bearing the same name.

11. The observations comprised in the following pages refer exclusively to the flowering or phænogamous plants. The study of the cryptogamous classes has now become so complicated as to form almost a separate science. They are therefore not included in these introductory observations, nor, with the exception of ferns, in the present Flora.

12. Plants are

Monocarpic, if they die after one flowering-season. These include Annuals, which flower in the same year in which they are raised from seed ; and Biennials, which only flower in the year following that in which they are sown.

Caulocarpic, if, after flowering, the whole or part of the plant lives through the winter and produces fresh flowers another season. These include Herbaceous perennials, in which the greater part of the plant dies after flowering, leaving only a small perennial portion called the Stock or Caudex, close to or within the earth ; Undershrubs, suffruticose or suffrutescent plants, in which the flowering branches, forming a considerable portion of the plant, die down after flowering, but leave a more or less prominent perennial and woody base ; Shrubs (frutescent or fruticose plants), in which the perennial woody part forms the greater part of the plant, but branches near the base, and does not much exceed a man's height ; and Trees (arboreous or arborescent plants) when the height is greater and forms a woody trunk, scarcely brandling from the base. Bushes are low, much branched shrubs.

13. The terms Monocarpic and Caulocarpic are but little used, but the other distinctions enumerated above are universally attended to, although more useful to the gardener than to the botanist, who cannot always assign to them any precise character. Monocarpic plants, which require more than two or three years to produce their flowers, will often, under certain circumstances, become herbaceous perennials, and are generally confounded with them. Truly perennial herbs will often commence flowering the first year, and have then all the appearance of annuals. Many tall shrubs and trees lose annually their flowering branches like undershrubs. And the same