Latin name: Crocus sativus.
From: rnold.sanewssa.mnet.uswest.com (Robert G. Nold)
Crocus sativus comes up and blooms without autumn rain in Denver, and grows throughout the winter here, too. Like all fall-blooming crocus (of which there are many species), they go dormant in summer.
From: kcurr.cyberspace.com (Kaycee Curr):
...it is the threads that you would collect and dry. There are three of them (the stigmas) per crocus flower. (Over a million crocus flowers produce a pound of saffron- phew!)
From: lpdavies.bcfreenet.seflin.lib.fl.us (Leslie Paul Davies):
In planning your planting, estimate 6 mature plants will provide the stigmas for one small recipe.
From: chaseway.nbnet.nb.ca (wayne chase):
I have recently heard of a substitute for saffron. Dried Marigolds. Just air dry well and grind to powder. Use twice the amount of marigold as saffron to get same result.
From: melnick.stsci.edu (Rita Melnick):
Saffron comes from Crocus sativus, the saffron crocus. It is a fall blooming crocus. Each flower contains 3 red threads (stigma) that you pick, then dry, for culinary use. Be sure to get ONLY Crocus sativus, not the other fall-blooming crocuses, as they are NOT edible.
As for the marigolds, I'm not sure if the above advice applies to all varieties of marigolds, but I do know that it is true of the pot marigold, also known as Calendula. It gives the yellow coloring of saffron, but not the saffron taste. Turmeric is also a yellowing substitute for saffron. But nothing else tastes like saffron!