A crocus is a small flowering plant that blooms in very early spring, often pushing up through the last patches of melting snow. These cheerful flowers come in purple, yellow, white, or striped varieties, and they're usually some of the first signs that winter is ending.

Crocuses grow from corms planted in the fall, and they're remarkably tough. While most plants wait for warm weather, crocuses bloom when temperatures are still cold, sometimes appearing in late February or March. Their bright petals against gray dirt and white snow can feel like nature's way of saying “spring is coming!”

Gardeners love planting crocuses because they naturalize, meaning they spread and multiply on their own year after year. A few crocuses planted this fall might become dozens in a few years, creating a carpet of color each spring.

One species, Crocus sativus, produces saffron, the world's most expensive spice. Each flower has just three tiny red threads called stigmas, and it takes thousands of flowers to produce a single ounce of saffron. People harvest these threads by hand to flavor and color foods like paella and certain rice dishes.