Floral morphology and phenology of Sassafras tzumu (Lauraceae)

doi:10.1186/s12870-022-03714-6

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	Floral morphology and phenology of Sassafras tzumu (Lauraceae)
	Yang, Zhi ; Tan, Chao ; Wei, Yi-Min ; Rohwer, Jens G.; Liu, Bing 2; Yang, Yong
刊名	BMC PLANT BIOLOGY
	2022
卷号	22 期号:1
关键词	Flower Lauraceae Morphology Phenology Sassafras
ISSN号	1471-2229
DOI	10.1186/s12870-022-03714-6
文献子类	Article
英文摘要	Background Sassafras has been considered to belong to trib. Laureae of Lauraceae and has been assumed to have unisexual flowers. However, recent molecular phylogenetic studies have consistently suggested that Sassafras does not belong to the trib. Laureae but to Cinnamomeae and that it is nested within Cinnamomum. A recent morphological study revealed that one of the Asian species, S. randaiense, possesses bisexual flowers that are plesiomorphic in the family Lauraceae. As reports on the flower structure of the second Asian species, S. tzumu, have been contradictory, we wanted to ascertain if it has bisexual flowers or not. If the flowers were bisexual, could earlier reports that they were unisexual have been based on dichogamous flowering? Results In this study, we investigated two populations of S. tzumu. We found that this species has determinate botryoid racemes, and possesses bisexual flowers. Among the three extant species, S. tzumu is more similar to its sister species S. randaiense but markedly different from the American S. albidum: the two Asian species possess bisexual flowers while the American species has unisexual flowers. The bisexual flower of S. tzumu is protogynous, and shows two phenological phases typical of Lauraceae: 1) in a flower, the pistil functions first, the stigma is fresh and white, stamens of the outer two whorls are spreading, anthers do not open, and the staminodes secrete nectar at this stage; 2) in the second phase, the stigma becomes brown, staminodes are withered, stamens of the third whorl stand up and surround the pistil, glands of the third whorl of stamens secrete nectar, and the anthers open and release pollen. Conclusions The similarity of racemose inflorescences between Sassafras and some members of Laureae were caused by parallel evolution; the racemose inflorescence of ancestral Sassafras originated from the thyrsoid-cymose inflorescence in Cinnamomum. The Asian species S. tzumu and S. randaiense possess bisexual flowers with two phenological phases, the American S. albidum evolved unisexual flowers independently from other clades with unisexual flowers in the Lauraceae, i.e., the Laureae, Alseodaphnopsis in the Perseeae and the unisexual clade in the Ocotea complex of the Cinnamomeae.
学科主题	Plant Sciences
出版地	LONDON
WOS关键词	GENUS ; BIOGEOGRAPHY ; PHYLOGENY
WOS研究方向	Science Citation Index Expanded (SCI-EXPANDED)
语种	英语
出版者	BMC
WOS记录号	WOS:000821888900002
资助机构	National Natural Science Foundation of China [31970205] ; Natural Science Foundation of Jiangsu Province [BK20211279] ; Nanjing Forestry University
内容类型	期刊论文
源URL	[http://ir.ibcas.ac.cn/handle/2S10CLM1/28717]
专题	系统与进化植物学国家重点实验室
作者单位	1.Nanjing Forestry Univ, Coll Biol & Environm, Coinnovat Ctr Sustainable Forestry Southern China, 159 Longpan Rd, Nanjing 210037, Peoples R China 2.Rohwer, Jens G.] Univ Hamburg, Inst Plant Sci & Microbiol, Ohnhorststr 18, D-22609 Hamburg, Germany 3.Chinese Acad Sci, Inst Bot, State Key Lab Systemat & Evolutionary Bot, 20 Nanxincun, Beijing 100093, Peoples R China
推荐引用方式 GB/T 7714	Yang, Zhi,Tan, Chao,Wei, Yi-Min,et al. Floral morphology and phenology of Sassafras tzumu (Lauraceae)[J]. BMC PLANT BIOLOGY,2022,22(1).
APA	Yang, Zhi,Tan, Chao,Wei, Yi-Min,Rohwer, Jens G.,Liu, Bing,&Yang, Yong.(2022).Floral morphology and phenology of Sassafras tzumu (Lauraceae).BMC PLANT BIOLOGY,22(1).
MLA	Yang, Zhi,et al."Floral morphology and phenology of Sassafras tzumu (Lauraceae)".BMC PLANT BIOLOGY 22.1(2022).