50.  Plantago lanceolata.  Rib-grass.—­This is a perennial plant, and very usefully grown, either mixed with grasses or sometimes alone:  it will thrive in any soil, and particularly in rocky situations.  It is much grown on the hills in Wales, where by its roots spreading from stone to stone it is often found to prevent the soil from being washed off, and has been known to keep a large district fertile which would otherwise be only bare rock.  Sheep are particularly fond of it.  About four pounds sown with other seeds for pasture, will render a benefit in any situation that wants it.  Twenty-four pounds is usually sown on an acre when intended for the sole crop, and sown under corn.

51.  Poterium Sanguisorba.  Burnet.—­This plant grows in calcareous soils, and is in some places much esteemed.  On the thin chalky soils near Alresford in Hampshire, I have observed it to thrive better than almost any other plant that is cultivated.  Sheep are particularly fond of it; and I have heard it said that the flavour of the celebrated Lansdown mutton arises from the quantity of Burnet growing there.  It is also the favourite food of deer.  This will grow well in any soil, and there are few pastures without it but would be benefited by its introduction.  Twenty-five pounds per acre are sown alone:  eight pounds mixed with other seeds would be sufficient to give a good plant on the ground.

52.  Sanguisorba officinalis.  Great Canada burnet.—­Cattle will eat this when young; and it has been supposed to be a useful plant, but I do not think it equal to Burnet.

It is perennial, and is often found wild, but has not yet been cultivated.

53.  Trifolium pratense.  Red clover.—­This is a very old plant in cultivation, and perhaps, with little exception, one of the most useful.  It is very productive and nutritive, but soon exhausts the soil; and unless it is in particular places it presently is found to go off, which with the grazier is become a general complaint of all our cultivated Clovers.  It is also well known, that if the crop is mown the plant is the sooner exhausted.

Seeds of Clover have the property of remaining long in the ground after it has become thus in a manner exhausted; and it frequently occurs that ashes being laid on will stimulate the land afresh, and cause the seeds to vegetate; which has given rise to the erroneous opinion with many persons, that ashes, and particularly soap ashes, will, when sown on land, produce Clover.

Red Clover is usually cultivated in stiff clays or loamy soils; and when sown alone, about sixteen or eighteen pounds of seed are used for the acre.

54.  Trifolium medium.  Zigzag, or Mountain-clover.—­Is in some degree like the preceeding; it produces a purple flower, and the foliage is much the same in appearance:  but this is a much stronger perennial, and calculated from its creeping roots to last much longer in the land.  It is equally useful as a food for cattle, and does not possess that dangerous quality of causing cattle to be hove, or blown, by eating it when fresh and green.  This plant is, however, only to be met with in upland pastures, and there in its wild state; for it does not seed very abundantly, and is not in cultivation.