Double fertilization and seed formation of Calycanthus chinensis

Double fertilization and seed formation of Calycanthus chinensis Cheng et S .Y .Chang were observed .It was showed that pollen tube got to embryo sac from micropylar in 8 days after the pollination .Double fertilization occurred in 10 ～ 13 days .Primary endosperm nucleus took a short dormant undergo free nuclear division .In about 18 days , the one-lined endosperm became cellular , belonging to a nuclear type .And zygote began to divide after one week dormant , and embryogenesis merges in to an oragrad type .Heart-shaped embryo developed in 39 days , then two pieces of cotyledon grew in one direct to surround the endosperm .With development of embryo , nucellus and inner integument were consumed .Endosperm differed in shape :the cells of which connected to embryo was much smaller , higher cytoplasm and the cells in central part showed much larger , extended in vertical direct , the cells in chalazal also differed in shape .This structure showed passage by which nutrition absorbed by endosperm cells in chalazal was transported to embryo .There was a specific structure in endosperm development .We called it whole endosperm haustorium .