Which drink with thirsty mouths the vital juice, To this deny, to that, admittance give. BLACKMORE. Obs. 1. Of the different distinctions of leaves only, according to their position and form, above one hundred are enumerated. In all of them, one of the offices is, to subtilize and give more spirit to the abundance of nourishing sap, and to convey it to the little buds. There are two orders of veins and nerves in leaves, one belonging to each surface; and it has been generally observed, that the under side of the leaf, has the ramifications larger, and are capable of admitting a liquid to pass through them which those of the upper surface will not. The under side of the leaf is supposed to be intended for receiving, preparing, and conveying the moisture imbibed from the rising vapours of the earth, by which trees and plants are greatly nourished; so that one principal use of leaves is to perform, in some measure, the same office for the support of vegetable life, as the lungs of animals do for the subsistence of animal life. 2.Another of the great functions for which the leaves of trees and plants are designed, is that of their footstalks nourishing and preparing the buds of the future shoots, which are always formed at the base of these foolstalks. Leaves, moreover, are designed to shade the buds for the future shoots from the sun; which would otherwise exhale and dry up all their moisture. Airevi dently passes in at the leaves and goes through the whole plant, and out again at the roots. If the leaves have no air, the whole plant will die. This has been proved by experiments with the air-pump. And plants not only draw through their leaves some part of their nourishment from the air, but, the leaves also perform the necessary work of altering the water received in at the roots into the nature and juices of the plant; and hence it is, that the life of the plant depends so immediately on it leaves. 431. Every plant consists of a root, buds, a trunk or stem, of leaves, of props or arms, of the inflorescence; and of the parts of fructification. 432. In regard to their bulk, plants are divided into trees, shrubs, under-shrubs, and herbs, which last die in the winter. According to their respective durations, they are annual, lasting one year, and reproduced from their seed; or biennial, when they are produced in one year, and flower the next; perennial, when they last many years, as trees. 433. Plants, in regard to the roots, are bulbous, as in onions or tulips; tuberose, as in turnips or potatoes; and fibrous, as in grasses. They are deciduous, when their leaves fall in autumn; and ever-green, when they are constantly renewed, as in most resinous trees. They are said to sleep, when they change the appearance of their leaves or flowers at night. They are indigenous or native; and exotic or foreign. 434. The parts of fructification consist of the calyx, or cup, which is the outer green covering of a flower. The corolla are the delicate leaves or petals of the flower generally coloured, and are the parts which constitute the beauty of the flower. The nectary, or nectarium, is the part within the corolla which secretes the honey. 435. The calyx and corolla are fine expansions of the outer and inner bark or rind of the plaut; and their evident purpose is, to protect certain delicate extensions of the pith and wood, which grow within the corolla, and are called the pistil and the stamen, by the peculiar or ganization of which the seed is produced. 4 436. The pistil is provided ni its head with a gummy matter, and the stamen with a fine dust called pollen; and when the dust falls on the head of the pistil, it is there absorbed and carried down the style of the pistil to the germen or seed-vessel in the centre of the flower; where the seed is, in consequence, produced within a pericarp, afterwards called fruit, 437. Fruits, which afford us so many luxu ries, are, in fact, nothing more than the covering, or the natural means for protecting the seed of plants, and called, by Botanists, Peri "arps. Some pericarps are pulpy, as those of ap ples, pears, nectarines, &c.; some are hard, as unts; and some scaly, as the cones of firtrees. Your contemplation further yet purane 4 The wondrous world of vegetables view ! BLACK MORE. 438. It must not then be forgotten, that the design of the beautiful flowers which cover the earth is to create the seed of future trees, that the leaves, or corolla, of the flowers are merely protections of the delicate pistil, stamen, and germen; that in this last are produced the seeds and that for their protection is provided the pericarp, which we call the fruit. Go, mark the matchless workings of the Power In colour these, and those delight the smell g COWPER. 439. Linnæus seized on the variations in the number of the stamens as a means of classing the vegetable kingdom into twenty-four deno minations. Those flowers having one pistil, and but one stamen, he called mon-andria; those of two stamens he called di-andria; three, tri-andria ; so on up to twenty stamens, and above twenty, polyandria. When he found stamens in one flower, and. pistils in another, on the same plant, he called them diacia; and on different plants, polygamia. When altogether invisible, cryptogamia. 440. Nothing can be more easy than to remember the names of these 24 classes; they are, 1. Monandria, one stamen. 2. Diandria, two stamens. 6. Hexandria, six stamens, all of equal length. P 7. Heptandria, seven stamens. 8. Octandria, eight stamens. 9. Enneandria, uine stamens. 10. Decandria, ten stamens, I parate, 11. Dodecandria, twelve stamens inserted on the receptacle, 12. Icosandria, twenty or more s serted upon the calyx or corolla. 13. Polyandria, many stamens. 14. Didynamia, four stamens, tv short, 15. Tetradynamia, six stamens, for short. 16. Monadelphia, filaments united but separate at top. 17. Diadelphia, filaments unite sets. 18, Polyadelphia, filaments unite or more sets. 19. Syngenesia, filaments united, stamens. 20. Gynandria, stamens inserted o til, or on a pillar elevating the pistil. 21. Monacia, stamens and pistils: corollas, upon the same plant. 22. Diæcia, stamens and pistils corollas, upon different plants. 23. Polygamia, various situation only, or pistils only. 24. Cryptogamia, stamens and pis spicuous. |