Influences of Hormone Treatment and Temperature Stratification on Morphological After-ripening of Magnolia sieboldii K. Koch Seeds Polyethylene Glycol Fractionation Analysis of Low-Abundant Proteins in Magnolia sieboldii Seeds Age structure and niche of the endangered Magnolia sieboldii in Huangshan Mountain Reproductive Strategy of Endangered Plant Magnolia sieboldii in Sanqing Mountain Pollen Morphology and Viability of Magnolia sieboldi Effect of Treatment with GA3 and Variable Temperature Stratification on Germination and Endogenous Hormones of Magnolia sieboldii Seeds