FLAX HARVEST - Location photo shoot : Vlissegem, Belgium. Harvest was in June. • Flax (Linum usitatissimum) is a plant in the flax family (Linaceae). It is a crop that has been cultivated for a long time. There are blue-flowered and white-flowered varieties. There are also varieties with brown seeds and varieties with yellow seeds. The seeds of flax (linseed) are about 5 mm long. The varieties can be classified by use as follows : -Fibre flax: for linen, grown for more than six thousand years. -Oil flax: for linseed oil.