Geophyte: A plant that survives an unfavourable period by means of underground food-storage organs (e.g. rhizomes, tubers, and bulbs). Buds arise from these to produce new aerial shoots when favourable growth conditions return.*
These Crocus plants survived winter by storing energy underground in their corms.
*Allaby, M. (2006). A dictionary of plant sciences (Revised ed.). Oxford: Oxford University Press.