the sheath of the latter being a continuous tube in which the solid and often triangular culm is inserted, not folded.

The Ligule. At the point where the sheath ends and the lamina begins there is a thin and white semi-transparent membrane which is called the ligule. (See fig. 3.) As the botanical works which are most in use give very meagre descriptions of this organ, and as it is of the greatest use in diagnosis, it may be desirable to give here some of the terms employed by writers on the grasses to distinguish its various appearances. It is said to be entire, when it has no segments, or when there are no indentations in its exterior boundary line; bifid, when it is divided at the apex into two parts; lacerated, when it appears as if torn on the margin; ciliated, when the margin is set with short projecting hairs; truncated, when the upper part terminates in a transverse line; acute, when it has a short, sharp point; acuminated, when it has a long projecting point.

Its value as a distinctive character may be drawn from a comparative examination of P. pratensis and P. trivialis, which look exactly alike in their external aspect, but may be exactly distinguished by an examination of their ligules. They are truncated or obtuse in the former and long and pointed in the latter. The value of this organ in diagnosis arises from its remarkable constancy in the same species. Mr. Sinclair says: "I have raised a great many species of different grasses from seed, under different circumstances as to soil and situation, with a view to obtain varieties from them. I found many of the plants thus raised to vary from the parent in the number of the florets, in the presence or the want of hairs on the surface, and sometimes, though rarely in the awns; but in no instance did the form of the ligule vary. Being thus constant, it may be depended on." This statement corresponds with my own experience. Writers on the subject say that the use which this part of the leaf subserves is that of more securely fastening the upper part of the leaf to the culm, when the wind tends to tear the leaf downward; but those grasses that are unprovided with ligules are no more liable to this accident than those that have them, and they are, besides, too thin and delicate to add much to the strength of the attachment. We fear it will be the wisest course to acknowledge that we are wholly ignorant of its uses.

The Lamina, blade, or flat part of the leaf is the expanded portion. It is sometimes large and drooping, as in elymus and zizania; occasionally it is very minute, especially when compared with the sheath, as in Avena pubescens and Festuca ovina. In some species

the blade is long and the sheath is short, as in Festuca duriuscula. The lamina is traversed by longitudinal parallel lines, which are known as the leaf veins, nervures, or simply nerves; these may be broad, narrow, rigid, soft, armed with rough hairs which sometimes point forward, sometimes backward; others have the hairs only on the back of the leaf; others only on the upper side; some have them only on the nerves, and some only on the edges, while some are covered with them everywhere. These differences are all very useful in marking the distinctions of species and in indicating their agricultural values, as, for instance, grasses in which the herbage is covered with long downy hairs, are mostly poor and innutritious in quality; on the other hand, those of a harsh and rigid structure, with serrated leaves, whose edges act as a saw, and whose flat blades perform the office of a file, even if they were nutritious, would, nevertheless, be rejected by cattle on account of their mechanical inconveniences. 4. THE FLOWER consists of:

(a) Floral envelopes.

(b) Fertilizing organs.

The floral envelopes are composed of the Glumes (see Figs. 4 and 6) or outer husks, which are the equivalents of the calyx in other flowers, and of the Palea, sometimes called glumule or inner huske (Fig. 5) which are equivalent to the corolla of other flowers.

Very many points of distinction are afforded by the floral envelopes. The glumes differ greatly in shape and in the presence or absence of longitudinal lines or ribs or nerves. They may be large enough to iuclude or conceal the paleæ, or they may be very much smaller, so as to allow the latter to be seen towering above them. The inner and outer valve may differ in size or shape, as, for instance, in the Panicum family, where one of the valves is so small that it may be overlooked without close scrutiny; others, such as Paspalum, have but one valve. Some difficulty is experienced by beginners in distinguishing between the inner and outer glume; but a careful examination of the lower part of the glume will always make this matter quite clear. On examining any species of grass, or figure 6, it will be clearly seen that one of the valves overlaps the other, at least at the base, and this overlapping valve is always the outer. It will also be well to bear in mind that the outer is likewise called the lower glume, and that the inner is in like manner called the upper.

The palese are more constantly resorted to than perhaps any other part of the plant to determine distinctions in species. To examine them to the best advantage, we must be provided with spring forceps,

and cambrick needles inserted in wooden handles, and a good pocket magnifying glass. They are subject to great differences in form and structure; some are covered with hairs, as Fig. 12, which is a magnified view of the paleæ of bromus mollis, and some have the hairs only on particular parts, as the edges, as is seen in Fig. 13, which is a magnified view of the paleæ of bromus racemosus, where the edges of the inner palea are ciliated. Some are awnless, others have straight awns, as in Figs. 12 and 13; some are bent, some are twisted, some are both bent and twisted, as in Fig. 14, which gives a magnified view of the palea of trisetum pratense. The place where the awns are inserted on the palea must also be noted; some are inserted at the bottom of the palea, others in the middle, others just below the top, others proceed from the very tip, and are, in fact, prolongations of the mid rib. In some the awns are longer than the palea, in others they are shorter, and in some they are of equal length. The nerves of the palea must also be noted; they vary in prominence and in number; in some there is only one nerve, in others three, and in others five. The paleæ differ in shape; some are round, others are keeled like a boat. Whoever will examine any member of the genus poa, will see at once what is meant by a keeled palea, and he will understand it still better if he will compare it with any of the fescues which have rounded paleæ. The most usual mode of discriminating between a fescue and a poa is to look and see whether the palea and glume are keeled, if they are so, it is said to be a poa; this test also decides between poas and glycerias. Some paleæ are grooved transversely, others longitudinally. Some have only a single palea, as in some species of agrostis. Their organs present so many and such definite marks, that the student will be well repaid for the most thorough and repeated study of all these peculiarities.

The FERTILIZING ORGANS consist of the stamens and pistils.
The stamens are constituted by the following parts:

The filament, which is a long flexuous hair-like body, seen in Fig. 7, springing from the base of the ovarium, springing upward and outward, then curving over about on a level with the top of the ovarium and inserted into the middle of the anther.

The anther is the box in which the pollen is secreted, and is deeply notched at both ends, as seen in Fig. 7. The line running through the middle is called the connective; there is a pollen cell upon each side of it; when the pollen is ripe the edges of the anthers burst open, and the pollen is scattered on the stigma of the pistil and thus fecundates the seed.

The pollen is the fecundating dust of the seeds; among the grasses its color is, we believe, always yellow. In grasses the pollen grains are spherical. By watching the grasses as they come into flower, the whole process of dehiscence, as the opening of the anthers for the discharge of pollen is called, can be distinctly seen, and the pollen grains may be examined with a microscope. The anther is not much used in discriminating one species from another. The only thing to be observed is whether the filament and anther is longer or shorter than the flower. In the former case it is said to be exserted; in the latter, it is inserted. With a few exceptions the grasses of this country have three stamens; those, therefore, that have less than three are easily identified. The pistil is constructed with a style and a stigma. See Fig. 7. Our grasses have two styles each, having a feather like stigma. The pistils of our grasses resemble each other so closely that little use can be made of them in diagnosis.

5. The seeds or fruit vary very considerably in the different varieties, but these differences are very difficult to describe intelligibly, without specimens. Those who desire to study this part of the subject more fully, are referred to Mr. Sinclair's Hortus Gramineus Woburnensis, where they will find the seed of every species of grass accurately figured and described.

Having thus described the separate parts of a grass, we will now endeavor to explain the terms used to describe them in their aggregation. It is the more necessary for the reader to charge his memory with these details, as this part of the subject is much neglected by the authors of our elementary treatises on botany.

Herbage, denotes the leafy portion of the grass, and is that which chiefly concerns us in pasture. The quality of grass depends so much upon the quantity and physical character of the herbage, that for agricultural purposes, these should be studied with great care. If for hay, both bulk and quality are much influenced by luxuriant leafage, a character in which grasses will be found to differ in a remarkable degree; if, however, this be rough and unpalatable, that is, if it is the "sour grass" of the farmer, no matter how great is its quantity, its growth should be discouraged. Again, if it is to be depastured we must note such facts as its longevity, and the manner that it bears the constant mutilation arising from the bite and tread of cattle. Duration is also a very important element, as for permanent meadows and pastures, perennial grasses are indispensable; while for alternate husbandry, the aunual or biennial varieties are best adapted, since the cultivated crop can be obtained much freer from foreign growth with

the latter than with the former. The culms of grasses should be carefully considered with reference to their physical qualities; whether they are hard or wiry, soft or pliable, bitter or saccharine, scanty or abundant, should be ascertained, as the hay will be dependent on these circumstances with respect to quality and bulk.

Heads of flowers are aggregated from single spikelets or smaller bunches or bundles of flowers, which may vary in the following manner: 1. A single palea to each glume.

2. Two palex to a glume.

3. Three or more pales to a glume.

The use of the term spikelet is sometimes very puzzling to beginners, as it is not very carefully defined in our botanical books. It will help us to remember that in a great majority of cases it means all the florets subtended by a single glume; and that in a very few others, such as Elymus and its allies, it means the flowers collected within a single involucre. In this way all difficulty and confusion will be avoided.

Each spikelet is attached to the rachis or upper central stem. (a) Directly to the stem itself, when it is said to be sessile or

(6) By a short upright footstalk, which is called a pedicel; in either case (a or b) the flowers are united into a compact cylindrical form called a spike, as in timothy (Phleum pratense), crab grass (Setaria glauca), or meadow foxtail (Alopecurus pratensis).

(c) They are on longer pedicels, forming an upright panicle as in Aira flexuosa or Festuca pratensis.

(d) On long and flexible pedicels forming a drooping panicle as in Bromus secalinus.

DISTINCTIONS OF QUALITY IN GRASSES.

Grasses are not only distinguished from each other by differences in their external forms, but also by differences in their quality and the amount of nutriment that they afford. Mr. Sinclair, in view of his observations and experiments, is of the opinion that those grasses which are most closely allied to each other in their physical appearance are also most nearly related in the quantity and quality of the nutriment that they afford. Mr. Sinclair expresses his conclusions in the following words.

First. Grasses which have culms with swollen joints, leaves thick and succulent, and flowers with downy husks, contain a greater proportion af sugar and mucilage.

Second. When this structure is of a light glaucous color, the sugar