lignify

The stone cells came from the thin cell walls by the walls thicken and then lignifying;

砀山酥梨石细胞是由果肉中薄壁细胞壁加厚，继则木而成的；

Physiological mature of bud is the base of grafting,and semi-lignify is considered as the index of walnut grafting at growing stage.

植物芽的生理成熟是对植物嫁接的基础,核桃生长期嫁接均采用半木为指标。