Floral Morphology of Populus lasiocarpa Oliv and Its Phylogenetic Position in Populus Study on in Vitro Regeneration of Style-Stigma-Like Structure in Crocus sativus L. The Earliest Normal Flower from Liaoning Province, China Chemical Constituents of Essential Oils from Michelia alba Dc. at Perianth Development Stages by GC-MS Role of winged perianth in germination of Haloxylonh (Chenopodiaceae) seeds Delimitation and phylogeny of Aletris (Nartheciaceae) with implication for perianth evolution