Crocus – Evolution and Domestication
Bjarne Larsen
dept. Agriculture and Ecology, Copenhagen University
The genus Crocus contains about 80 species of corm-bearing perennial geophytes. Crocus grows generally in mountainous areas from sea level up to 2500 m, mostly on limestone ground in winter rain areas around the Mediterranean Sea. The largest diversity of species is found in Turkey, but species are found all the way from Portugal /Spain in west to Western China in east. Characteristic for most species is a limited geographical distribution where species have adapted to specific habitats. The flowering season of Crocus is almost throughout the year depending on species. The diversity of a number of the spring-flowering species is used for ornamental purposes. Hybrids between C. biflorus and C. chrysanthus have arisen during the last hundred years, resulting in a wide range of flower colors and shapes, which has gained popularity as early spring garden plants.
One of the most valuable crocuses, is the saffron crocus, Crocus sativus. This autumn-flowering species are grown for the world’s most expensive spice, saffron. C. sativus has been cultivated 4000 years back in time but is not known to occur in the wild. The ancestors of this triploid (2n=24), sterile species is not known, but C. cartwrightianus, a closely related diploid (2n=16) species from the Attica peninsula of Greece is believed to have taken part in ancient hybridization events resulting in C. sativus. This unique hybridization event has since then given corms to all the world’s saffron crocuses by vegetative reproduction.
The enormous diversity of Crocus represents a history of massive hybridization and specialization. Inter- and intraspecific variation suggests that the genus during evolution has been exposed to huge adaption demands and selection pressure.
