Fig. 1

Developmental stages established for the cork oak acorn. a Cork oak fruits collected at different developmental stages (S1-S8). The scale bar corresponds to 1 mm in S1 to S3 and to 5 mm in S4 to S8. b Cork oak fruits at stages S3-S5 after removal of the cupule (above), or cupule and pericarp (below) exposing the seed, and acorn measurement parameters (S7) used for acorn staging. D, maximum diameter of the acorn; P_i, portion of the acorn outside the cupule; P, acorn portion covered by the cupule. The scale bar corresponds to 1 mm in S3 to S5 and to 5 mm in S7