Oat, or Avena, L. a genus of plants, comprising 33 species, of which the following are the principal : and the six first mentioned are natives of Britain; namely,

I. The nuda, Naked Oat, Pilcorn, or Pills, growing wild in some parts of Staffordshire, and flowering in the month of July.- This species is cultivated in the county of Cornwall 3 where, in the time of Ray, it was sold at the price of wheat. It is reputed to be nearly as good as the common oat ; for it yields excellent meal; is equally useful in feeding cattle 3 and thrives on the poorest lands.

11. The elatior (Holcus aven-aceus of Dr. Smith), Tall Oat-grass, or Oat, thrives on wet, damp soils; in meadows, pastures, and hollow ways ; it flowers in the months of June and July.—This grass vegetates with uncommon luxuriance ; and, though somewhat coarse, it makes tolerably good hay. It is eaten by cows, goats, and sheep, but is frequently very troublesome in arable lands 3 as its roots spread in a manner similar to couch-grass, and are very difficult to be eradicated.

III. The fatua, Bearded Wild Oats, Hover, or Haver, is found in corn-fields, where it flowers in the month of July or August.-This species is eaten by horses, sheep, and goats : it is a pernicious weed in corn-fields, particu-Jarly among barley, where it is sometimes so prevalent, that it almost entirely choaks the growth of the latter. It may be extirpated by repeated fallowing, or by laying the land down to grass.

IV. The pubescens, Rough Oat, Downy Oat-grass, or Hairy Oat-grass, which grows on dry meadows, in chalky situations, and flowers in the month of June. It is refused by every species of catlle; and, on account of its roughness, does not deserve to be cultivated.

V.The ftavescens, Yellow Oat, or Oat-Grass, thrives in meadows, pastures, and on hills, in a calcareous soil, and flowers in the months, of June and July.- This species, though tolerably sweet, is inferior to the meadow and fescue-grasses. Dr. Withering observes; that cattle do not relish it, but Mr, Swayne states it to be one of the best of this genus, for the use of the farmer.

VI. The praleusis, Meadow Oat, or Narrow-leaved Oat-grass, is likewise a native of Britain, growing on heaths, and high calcareous lands ; flowering in the month of July - This species is a tolerably good pasture-grass, and particularly calculated for poor stony soils; as it prospers, where the meadow-grasses will not vegetate.

VII. The sativa, or Common Oat, thrives on almost any soil ; and, being extremely productive on land, newly broken up, it is emi- nenthy nently adapted to cold mountains, or marshy ground. It is divided into three varieties, namely :

1. The White Oats, which are the most valuable, and require a soil somewhat drier than that for the other species : this variety is chiefly cultivated in the southern counties of Britain.

2. The Black Oats, which are principally raised in the northern parts of this island : - for feeding cattle, they are of equal quality to the white oats; though not affording so sweet a meal for culinary purposes, as the latter.

3. The Brown, or Red Oat, produces good meal ; ripens somewhat earlier than either of the two preceding varieties, and does not shed its seed. It is chiefly cultivated in the north-western parts of England, for the feeding of cattle.

All these varieties are propagated by seed, which may be sown from the middle of February to the beginning of June, in the proportion of from three to six bushels per acre, broadcast ; though sometimes with the addition of 121bs. of clover, and one bushel of ray-grass. The seed is harrowed in ; and the management of this kind of grain does not materially differ from that of barley, rye, etc. Oats have, in the south of Britain, been both dibbled and drilled; but, as this new practice has been attempted only by a few farmers, the success has not been completely ascertained ; though there is little doubt but that either method, if judiciously conducted, is preferable to the broadcast system.

The last-mentioned species is raised on account of its farinaceous properties. The grain is given to horses, for which it affords a very Strengthening food; and, before barley came into general cultivation, it was converted into malt.

The meal is, in North Britain, made into cakes, biscuits, etc.; or it is boiled into a kind of pottage. Lastly, its soft straw is usefully employed in feeding cattle, when mixed with potatoes; and likewise for packing glass and earthen-ware.

Beside the three varieties into which the common oat is divided, there are two others, which have originated from them, namely :

1. The Peebles-oat, is a variety of the red-oat, and which was first cultivated in the Scotch county of that name. It is peculiarly calculated for mountainous districts, as it not only ripens early, but also withstands the severity of the wind, and is not easily shaken. Its grains, though smaller than those of any other oat, have a very thin hull, and yield an unusual proportion of fine, wholesome meal.

2. The Angus-oat, which has in a similar manner been denominated from the county of Angus, ii. cot-land ; and is a variety of the white-oat, but produces a better-bodied grain, together with a greater quantity of straw ; and is thus eminently adapted to poor, dry soils. It attains to maturity somewhat later in the season than its original common white kind.

VIII. The stipiformis, or Skegs, is an exotic grain, that flourishes on the poorest soils, and is propagated by sowing it in the proportion of two Winchester bushels per acre. The crops produced by this species, generally amount to double the quantity of other oats ; though in weight they are only equal.- Skegs is reputed to afford a remarkable sweet and wholesome food for horses, and cows, especially when given them together with the T4 straw; straw ; as likewise for ewes before they drop their lambs, whether allowed in the straw, or chopped ; which latter method, however, is more economical.

IX. The Tartarian, or Reed-oat, is conjectured to be a species unnoticed by LINNAEUS.. It appears to be well calculated for land that has been exhausted by an injudicious rotation of crops, and will also thrive on a stiff soil, where the common white-oat does not prosper. Its grain is much inferior to the generality of oats : nor does it ripen so early, or afford an equal proportion of meal; but its straw is very luxuriant, and the grain is not easily scattered by the wind.

X. The Fries land, and Poland-oats, which have received their names from those respective countries, are chiefly distinguished by their coming early to maturity. They, however, thrive only on the richest soils; easily shed their grain, when ripe; and afford a very indifferent meal, though they sometimes yield an astonishing increase. The quantity usually sown is, seven or eight bushels of the Poland, or six of the Friesland-oats, per acre, in the month of March or April: these species are chiefly consumed in feeding horses.

There is a variety of the Poland grain, first raised in Scotland, and all is called Churcuhs-oat. It eatly esteemed in Northumberland, as being the best of the ear-.lier-sorts, hitherto known, for sowing on loamy lands in good condition. This variety is very produc-tive, and ripens early; it is known by the grains being remarkably short, round, plump, and well fill-ed : it yields an excellent meal, and is easily converted into flour. Oats are subject to the smut, and various other diseases, and also to the depredations of numerous in-sects, in common with wheat, bar ley, etc. (see vol. i. p. l7l, .and vol. ii. pp. 65, 66) ; but they are most materially injured by a kind of grub, which peculiarly attacks them. This pernicious insect comes into existence, if the autumn has been warm, toward the end of October ; and progressively increases in size till the beginning of winter ; during which it continues stationary, without being injured by the most intense cold. Toward the end of February, the grub recommences its devastations, and gradually becomes larger till early in May, when it is more than an inch long, and one-third of an inch in circumference. At this period, it commits the greatest depredations, cutting, in a very short time, through the strongest stalks of grain.

In the summer, the oat-grub undergoes similar transformations with the caterpillar. While in its reptile state, this pernicious insect is almost invulnerable, and the fly is equally hardy. The only period, when it is susceptible of injury, is during its passage from the state of a grub to that of a chrysalis, about the end of May, or early in June, at which time rain and cold weather equally accelerate its destruction. And, as considerable quantities of rain fall during those months, almost the whole race perishes, excepting such as may have settled in soft, dry mole-hills, or on the coarse noxious weeds vegetating at the sides of ditches ; and the seeds of which are wafted into the contiguous fields, whither the eggs of the grubs are conveyed.

These destructive insects appear every year, but chiefly in wet situations ; tions: they are more or less numerous, according to the heat or cold of the former season. Were it not, indeed, for the vernal showers, which fall at the period above mentioned, such devastations would be irreparable. Nor has any better method of destroying them been discovered, than to clear every hedge and ditch of all coarse, rough weeds, and herbage ; for, as the latter afford shelter to the insects during the winter, they annually send forth a fresh stock, which neither fallowing nor any other attention can exterminate : thus, the soil is constantly infested with them, and much labour and expence are incurred, that might, with a little diligence on the part of the tanner, be effectually saved.

All the species of oats are very hardy plants ; and, as we have already observed, will flourish on al most every soil. Their strong roots, striking to a considerable depth, open the earth and thus, when •ploughed in, loosen it for other vegetables. But, though the general practice is to sow pats between the months of February and June, yet they may be advantageously committed to the ground late in autumn, especially in mountainous situations; for they will thus not only ripen earlier, but will be enabled to resist the-violence of the equinoxial winds. Farther, it ap-. pears, that unripe, seed (namely, such grain as may have been cut before it was fully ripe, in consequence of the approach of frost), if carefully dried, will, on being sown in drills, yield as good crops as corn that has attained to its full maturity. This - practice has been successfully proved by Mr. DUCKETT ; and, as it may be applied to wheat, it promises to be attended with the greatest advantage to farmers in exposed situations ; as they may thus make use of their ripe grain for flour, while the thin corn will serve for seed.

When deprived of their husks, and formed - into groats, oats are converted into an excellent dish for the infirm and diseased. When ground into meal, and boiled in water, they afford a thick and nourishing mucilage, which, with the addition of a few currants, is very wholesome, and produces a mildly laxative effect.