Cytochemical Localization of Pectinase: the Cytochemical Evidence for Resin Ducts Formed by Schizogeny in Pinus massoniana Studies on the Histology and Ultrastructure of the Initiation of Rhizoids and Protocorm-like Bodies(PLBs)Induced from the Leaf Explants of Rosa canina Studies on the Histology and Ultrastructure of the Initiation of Rhizoids and Protocorm-like Bodies(PLBs)Induced from the Leaf Explants of Rosa canina Initiation and Development of the Ovulate Strobilus in Pinus tabulaeformis