Saffron is the orange-red stigmas attached to the base of the autumn-flowering crocus (Crocus sativus), in the Iridaceae (iris) family. Saffron has a pungent, earthy, bittersweet flavor and a unique, acid, haylike aroma. The saffron crocus is sterile and is propagated by dividing the corms (small underground bulbs). Saffron is legendarily the most expensive spice in the world by weight. However, because it's so concentrated, a few threads can flavor an entire dish. Seventy thousand flowers, gathered and cleaned by hand the same day that they open usually by the smaller fingers of women are needed to make one pound of dried saffron. Spain and Iran together account for more than 80 percent of world production of about 300 tons annually.
Saffron is essential for Mediterranean fish and seafood dishes such as bouillabaisse, paella Valenciana, and risotto alla Milanese. It flavors northern Indian binyanis, Persian rice pilaf, and some Indian milk-based sweets. Note that in large quantities (far more than is used in cooking), saffron is toxic. Unlike most spices, saffron is soluble in liquid. To extract the most color and flavor, soak it in a warm water, milk, broth, or white wine until the liquid turns bright yellowish orange, then add the liquid to a dish. It's healthy for heart.
Saffron should be bought whole from a reputable spice dealer as powdered saffron can be easily adulterated. Avoid cheap "saffron", which may come from safflower, turmeric, or marigold. The best saffron, that of Kashmir and Iran, includes only the deeply colored red-orange stigmas; less expensive saffron is bulked up with flavorless yellow stamens.