Fig. 1.

Details of origin of plant material used for culture initiation. a A young zygotic embryo-derived sporophyte showing the first two fronds, which were used as a source of primary explants. b A young somatic embryo-derived etiolated sporophyte showing the first two fronds, which were used as a source of secondary explants. Bracket shows an initial explant. G gametophyte, R adventitious root, SA shoot apex, 1st first frond, 2nd second frond