Which part of the crocus flower gives us saffron?

Answer

Each flower has three stigmas, picked by hand, which is why saffron is so costly.

Context

Saffron comes from Crocus sativus, an autumn-flowering crocus. Each flower has three red-orange stigmas, the upper tips of the female reproductive part, and these are removed and dried to become the spice. Britannica reports that about 75,000 blossoms are needed for a pound of saffron, roughly 0.45 kilograms, which explains the high price. The flowers open for a short period and are picked by hand, often early in the morning, and the stigmas are separated by hand as well.

The plant is a sterile triploid that does not produce viable seeds, so it is propagated by dividing underground corms. This means that the cultivated crop is essentially a clone that has been spread by people for centuries, with its origin thought to lie in the eastern Mediterranean or western Asia. Iran is described as the chief producer today, with smaller crops in Spain, India and other countries.

The distinctive properties come from several compounds. Crocin, a water-soluble pigment, gives the strong golden-yellow color, picrocrocin gives the bitter taste, and safranal, formed from picrocrocin during drying and storage, gives most of the aroma. Research papers on commercial quality use the levels of these three compounds to grade saffron. A common misconception is that saffron comes from the petals. Petals are discarded or used in other products, and cheap powders sold under the name are sometimes adulterated with other plant material or dyes, which is a reason quality testing is widely studied.