This very important order includes not only the common Grasses, but the Bread Corns, or Cereal Grasses—Wheat, Oats, Barley, Rye, and Maize; and the Sugar-cane and Rice. All these plants are botanically allied to the Sedges, but their stems are hollow, except at the joints, where they become solid; and their leaves, though sheathing the stem, do not unite round it. The flowers are produced in spikes, which are what are called spikelets. The glume, or calyx as it was called by Linnæus, is generally two-valved; and within it are two thinner smaller scales, or paleæ, which were called the corolla by Linnæus. Besides these, there are frequently two still smaller scales within the paleæ. There are generally three or six stamens, the anthers of which are two-celled, and forked at the extremity. There are two styles, either quite distinct, or combined at the base, and the stigmas are feathery. The pericarp is membranaceous, and adheres to the seed, forming a kind of caryopsides. The seeds contain a great deal of albumen, which, when ground into flour, becomes nourishing food. The stems, or culms, are hollow and articulated; the leaves, which are alternate, springing from each joint. The most important genera are Wheat (_Triticum_), Barley (_Hordeum_), Rye (_Secale_), Oats (_Avena_), Maize (_Zea_), the Sugar-cane (_Saccharum_), Rice (_Oryza_), and the Bamboo (_Bambusa_). Oats are not produced in spikes, but in loose panicles; and the male and female flowers of the Maize or Indian Corn are on different plants. CHAPTER IV. CRYPTOGAMOUS PLANTS. These plants are generally described as being without spiral vessels, and consisting only of cellular tissue; but spiral vessels are known to exist in the Ferns, and are said to have been found in the Mosses. Whether this be the case or not, it is evident that the plants included in this division are very different from all that have preceded them, and occupy a lower grade in the scale of vegetable creation. They are divided into two sub-classes: viz. the _Foliaceæ_, or those with leaves, and the _Aphyllæ_, or those without leaves; both of which are without visible flowers, though some have what are called anthers, and the Mosses have something resembling a style and stigma. They may also be said to have no seeds, for the spores, or sporules as they are called, are very different from the seeds of vascular plants, and they have neither cotyledon nor embryo. SUB-CLASS I. FOLIACEÆ. ORDER CCXI.—FILICES.—THE FERN TRIBE.