1Leaves terete or semiterete, or 3-5-angled, hollow
1'Leaves flat, sometimes V-shaped or keeled, not hollow
2Leaves terete or semiterete, with a wide central cavity, easily compressible, usually diameter more than 5 mm (except A. schoenoprasum with a diameter of 1-5(-7) mm)
2'Leaves 3- or 5-angled, with a narrow central cavity, diameter 1-5 mm
3Leaves terete, sometimes a few semiterete (check several leaves); mature bulbs distinct or indistinct, (narrowly) oblong to (narrowly) ovoid to elliptic
3'Leaves semiterete, flattened on upper surface (check several leaves); mature bulbs distinct, depressed globose to ovoid or obovoid (immature bulbs of multiplier shallot are narrowly oblong to narrowly ovoid). Variable!
4Bulbs indistinct, diameter of bulb and neck equal or diameter bulb up to 1.5 times larger than diameter of neck
4'Bulbs distinct, diameter bulb 1.5-2 times larger than diameter neck (see note under 4. A. fistulosum)
5Coarse plants; leaves fistulose, swollen in the centre, gradually tapering towards both ends, usually diameter more than 5 mm; flowers pale yellow; stamens exceeding the tepals
5'Plants of finer habit; leaves fistulose, not swollen, usually diameter less than 5 mm; flowers usually purple, rarely white; stamens shorter than tepals
6Bulbs not set on a rhizome; leaves 20-60 cm by 10-35 mm
6'Bulbs with several closely together on a rhizome; leaves 13-45 cm by 2-10 mm
7Mature bulbs indistinct, ovoid to oblong, not composed of increase bulbs, increase bulbs (if present) much smaller than main bulb
7'Mature bulbs distinct, depressed globose to ovoid, composed of cloves (increase bulbs), cloves as long as main bulb (immature plants of A. sativum resemble A. ampeloprasum but can be distinguished by the presence of cloves within the inner bulb-coat-leaves and by a typical garlic-smell)