Initiation and early development of the ovulate strobilus in Pinus massoniana

The paraffin section technique was applied in the study of the initiation and early development of the ovulate strobilus in Pinus massoniana Lamb. from September to April cultivated at the campus of South China Agricultural University.Result is as follows: In the middle of October, the primordium of ovulate strobilus occurred, its occurrence time varied between different aged ramets and different occurrence part. Morphology and cytohistological zonation appeared different between cone apex and the vegetative shoot apex. The vegetative shoot apex is thin and flat morphologically, and its cytohistological zonation pattern is an apical initial zone, a central mother cell zone, a cambium like transitional zone, a peripheral zone, and a rib meristem, while cone apex is coniform, and its apex structure consist of outer mantle and inner pith. In the early December, the first bract primordium was formed in the axil scale at the cone base, then bract initiation had occurred in acropetal direction. In the early January, ovuliferous scale primordial were acropetally formed in the axils of the developing bracts. At the end of February, the bract attained approximately their full size, and a pair of anatropous ovules were initiated on the adaxial surface at the base of the fertile ovuliferous scale. It lasted for more than four months from initiation of the ovulate strobilus to formation of anatropous ovules. The sub tropical winter weather has no apparent inhibition for the growth and development of the ovulate strobilus in Pinus massoniana .