Alfalfa is a perennial cultivated forage and green manure crop of the genus alfalfa (Medicago.L.) in the family of Leguminosae, with a long history of cultivation. It has a long history of cultivation. There are many existing ecological types and cultivars, and some of its agricultural traits vary with varieties, natural conditions and different management levels.

1. Root

The root system is taproot system, the root system is especially developed, the main root is thick, diameter 2.5-5.0cm, very deep into the soil, the main root of the year of sowing into the soil depth of up to 2.7m, 9 years of people into the soil up to 10m or more; the lateral roots are mainly distributed in the soil layer of 20-30cm; the root neck grows near the ground, 2-3 diameter of 1-3.5cm, the growth can reach 5.0cm or more, the upper part of which can grow to 5.0cm or more, and the upper part of which can reach 5.0cm. 5.0cm or more, the buds on which form aboveground stem branches; rhizomes are mostly concentrated on the lateral roots in the soil layer of 5-30cm, with the most in the soil layer of 20-30cm. In addition, the roots have branch-root type, rhizome type and root tiller type.

2. Stem

There are main stem and branch, the main stem is round or four-angled, colorless or slightly pilose, erect or obliquely ascending, the height is generally 50-120cm, and the highest reaches more than 150cm, and the branches from the base of the root neck can be as many as 25-40, and the most up to more than 100 branches.

3. Leaves

Generally pinnate ternate compound leaves, stipules large, ovate-lanceolate, petiole shorter than the leaves; terminal leaf blade slightly larger than the lateral leaf blades, leaf blades long ovate, long obovate-elliptic, or linear-ovate, long (5)10-25(40)mm, 3-10(12)mm wide, glabrous on top or pilose below. There are also compound leaves with 4, 5, 6, 7, and even 17 leaflets.

4. Flowers

Generally racemes, axillary, inflorescences (1.0) 2.0 to 2.5 (3.0) cm long, rarely up to 5.0 to 8.0 cm, (8) 15 to 20 (25) flowers, up to 40; common pedicel beyond the leaves, hairy; bracts linear-conical; flowers butterfly-shaped, 6 to 12 mm long; pedicel short, about 2 mm; calyx campanulate, 3～5mm long; corolla is generally purple, hence the name alfalfa, but also dark blue, etc., depending on the species; stamens dimorphic, anthers homomorphic, style slightly curved inward, pistil stigma capitate, ovary linear, sessile, with ovules 10 or so, the base of the ovary with nectaries.

5. Fruit

Pods spiral, spiral hollow, usually 1 to 3 circles, more often 5 circles, densely ambiguous hairs, or fall off, 3 to 7 mm in diameter, brown at maturity; containing seed seeds (2) 4 to 8 seeds, seeds ovate or reniform, yellow or brown, thousand grains weight 1.5 to 2.05 g.

Chromosome 2n = 32; karyotype formula: 2n = 4x = 32 = 28m + 4sm. 32=28m+4sm (SAT).

Alfalfa