Lettuce (variety. Lamosa Holt. ) is a common name for leaf lettuce, also known as goose feather lettuce, mashed lettuce and lettuce, belonging to the genus Lettuce in Compositae. It is an annual or biennial herb crop with long obovate leaves and dense cabbage shape, which can be eaten raw, crisp and slightly sweet. The flowering and fruiting period is from February to September.
Lettuce is an annual or biennial herb with a height of 25- 100 cm. The roots extend vertically. The stem is erect and solitary, with panicle branches on the upper part, and all the stems and branches are white. Basal leaves and lower stems and leaves are large, undivided, oblanceolate, oval or ovoid, 6- 15cm long and 1.5-6.5cm wide, with sharp tips, short cones or circles, no stalks, a heart-shaped or arrow-shaped semi-embracing stem at the base, wavy or serrated edges, and tapering upward, which are the same as those of basal leaves and lower stems and leaves. .
The heads are numerous or extremely numerous, arranged in panicles at the top of stems and branches. The involucre is ovoid, with a length of 1. 1 cm and a width of 6mm. The involucral bract has five layers, the outermost layer is triangular, about 65438±0mm long and 2 mm wide, the outer layer is triangular or lanceolate, about 5-7 mm long and 2 mm wide, the middle layer is lanceolate to ovate-lanceolate, about 9 mm long and 2-3 mm wide, and the inner layer is linear and rectangular, about 65438±0cm long and 2 mm wide. All involucral bracts are sharp at the top. Lingual florets are about 15. Achene is oblanceolate, 4 mm long, 65438 0.3 mm wide, flat, light brown, with 6-7 veinlets on both sides, and the tip is sharp and filiform, about 4 mm long, almost as long as achene. The crown hair is 2 layers, slender and slightly rough.