Belongs within: Iridaceae.
Crocus is a genus of low-growing herbs in which flowers arise at ground level with a subterranean ovary (Healy & Edgar 1980).
Characters (from Healy & Edgar 1980): Low-growing, more or less inconspicuous; flowers arising singly, one to several from a corm, at first stalkless and ovary subterranean; perianth-tube long, funnel-shaped, perianth lobes more or less spreading.
<==Crocus
|--C. angustifoliusV09
|--C. cancellatusPT98
| |--C. c. ssp. cancellatusPT98
| `--C. c. ssp. mazziariacusPT98
|--C. chrysanthusV09
|--C. cypriusD30
|--C. flavusHE80
|--C. multifidus Ramond 1800R00
|--C. nudiflorusV09
|--C. sativusC55
|--C. speciosusV09
|--C. × stellaris [C. angustifolius × C. flavus]V09
|--C. susianusKSM06
|--C. tommasinianusV09
`--C. vernusV09
*Type species of generic name indicated
References
[C55] Candolle, A. de. 1855. Géographie Botanique Raisonée: Ou exposition des faits principaux et des lois concernant la distribution géographique des plantes de l’époque actuelle vol. 2. Librairie de Victor Masson: Paris.
[D30] Druce, G. C. 1930. Account of a botanical tour in Cyprus. Proceedings of the Linnean Society of London 141: 50–52.
[HE80] Healy, A. J., & E. Edgar. 1980. Flora of New Zealand vol. 3. Adventive cyperaceous, petalous and spathaceous monocotyledons. P. D. Hasselberg, Government Printer: Wellington (New Zealand).
[KSM06] King, R. C., W. D. Stansfield & P. K. Mulligan. 2006. A Dictionary of Genetics 7th ed. Oxford University Press.
[PT98] Panitsa, M., & D. Tzanoudakis. 1998. Contribution to the study of the Greek flora: flora and vegetation of the E Aegean islands Agathonisi and Pharmakonisi. Willdenowia 28: 95–116.
[R00] Ramond, C. 1800. Plantes inédites des Hautes-Pyrénées. Bulletin des Sciences, par la Societé Philomathique de Paris 2 (41): 129–133.
[V09] Verdcourt, B. (ed.) 2009. Additions to the wild fauna and flora of the Royal Botanic Gardens, Kew. XXVI. Miscellaneous records. Kew Bulletin 64 (1): 183–194.