The Marsh Mallow has been much esteemed as a demulcent medicine, and an ointment is made from it for external use; but one species of this order, the Gossypium, is one of the most important plants in the whole world, producing that most useful article, cotton, so largely grown in America, and for which the slave population are chiefly employed. The fine white hairs surrounding the seeds and filling up the pod is the part picked out and preserved, it forms the cotton-wool of commerce, of which some eight hundred millions of pounds' weight are used annually! employing a million and a half people, in England alone, and furnishing clothing to hundreds of millions. It is grown in India, which is supposed to be its native place, and will probably be grown to a much greater extent when railways and canals shall have made a more easy communication from the interior of that country to the sea-board. [Illustration: Marsh Mallow.] 15. GERANIACEÆ (Geranium pyreniacum) Meadow Geranium. Many species of this order are indigenous, and when cultivated produce some of our most beautiful garden flowers, as the Geraniums, Pelargoniums, and Erodiums. The Geraniums are those species which have five irregular petals and ten stamens; they are the most characteristic of the order. [Illustration: Meadow Geranium.] 16. LINACEÆ (Linum usitatissimum) Common Flax. The Flax plant is another of those insignificant plants which, from certain properties they possess, have become the greatest boons to mankind; the stalks of the Linum usitatissimum, soaked, bruised, and prepared by combing, &c., form the flax of commerce, from which all our linen fabrics are made. The manufacture of flax is one of the oldest arts known, the ancient Egyptians formed their mummy-cloths from this article, and a piece of one of these cloths, bleached and placed side by side with some of the present date, would hardly suffer by the comparison, but the rapidity of its manufacture, and the price at which supplied, are doubtless very different in the two cases. [Illustration: Flax Plant.] The value of the linen manufacture of Great Britain is between seven and eight millions yearly. The seeds of the flax plant (Linseed) are used to crush and produce the linseed oil of commerce so extensively used in the production of paints and varnishes, and the cake is used as food for cattle. 17. ACERACEÆ (Acer campestre) Maple Tree. (Acer pseudoplatanus) Sycamore Tree. This order contains the Maple and Sycamore, fine trees, not only ornamental, but producing wood much in request, moreover the Acer saccharinum or Sugar Maple of North America is used to produce sugar, which is obtained from its sap. [Illustration: Maple Tree.] 18. RUTACEÆ (Ruta graveolens) Rue.