Flax, also called linseed, is the seed of Linum usitatissimum, a slender blue-flowered annual whose Latin name means the most useful flax — a fair claim for a plant that yields both a major oilseed and the fibre spun into linen. The small, glossy, teardrop-shaped seeds, brown or golden, taste mild and gently nutty. Crucial point: to get their renowned nutrition the seeds must be ground, because whole flaxseeds largely pass through the gut undigested. Ground flax is a baking staple and a vegan egg substitute, while the seed is pressed for linseed oil, and flax is exceptionally rich in omega-3 ALA, lignans and soluble fibre.