LETTUCE; a genus of the polygamia squamis order, belonging to the syngenesia clas of plants. There are several species, most of which are plants of no use, and never cultivated but in botanic gardens for variety. Those commonly cultivated in the kitchen-garden for use are, 1. The common or garden lettuce. 2. Cabbage lettuce. 3. Silexia lettuce. 4. Dutch brown lettuce. 5. Aleppo lettuce. 6. Imperial lettuce. 7. Green capuchin lettuce. 8. Verfailles or upright white Cos lettuce. 9. Black Cos. 10. Red Cos. 11. Red capuchin lettuce. 12. Roman lettuce. 13. Prince lettuce. 14. Royal lettuce. 15. Egyptian Cos lettuce.

The first of these sorts is very common in all gardens, and is commonly sown for cutting very young; to mix with other salad herbs in spring; and the second, or cabbage-lettuce, is only this mended by culture. It may be sown at all times of the year, but in the hot months requires to be sown in shady borders. The cabbage-lettuce may also be sown at different seasons, to have a continuation of it through the summer. The first crop should be sown in February, in an open situation; the others, at three weeks distance; but the later ones under covert, but not under the drippings of trees.

The Silexia, imperial, royal, black, white, and upright Cos lettuces, may be first sown in the latter end of February or the beginning of March, on a warm light soil, and in an open situation; when the plants are come up, they must be thinned to 15 inches distance every way, they will then require no farther care than the keeping them clear of weeds; and the black Cos, as it grows large, should have its leaves tied together to whiten the inner part. Succeeding crops of these should be sown in April, May, and June; and toward the latter end of August they may be sowed for a winter crop, to be preserved under glass, or in a bed arched over with hoops and covered with mats.

The most valuable of all the English lettuces are, The white Cos, or the Versailles, the Silesia, and the black Cos. The brown Dutch and the green capuchin are very hardy, and may be sown late, under walls, where they will stand the winter, and be valuable when no others are to be had. The red capuchin, Roman, and prince lettuce, are very early kinds, and are sown for variety; as are also the Aleppo ones for the beauty of their spotted leaves.

The milk of the common garden-lettuce is hypnotic, while the root of the plant is cooling, diluent, and nourishing.