title: A Late Devonian fertile organ with seed plant affinities from China.
abstract: Seed plants underwent first major evolutionary radiation in the Late Devonian (Famennian), as evidenced by the numerous ovules described to date. However, the early pollen organs are underrepresented, so that their structure and evolution remain poorly known. Here we report a new taxon of pollen organ Placotheca minuta from the Late Devonian. The synangium consists of many basally and more or less laterally fused microsporangia borne on the margin of a pad. The prepollen is spherical and trilete. The appearance of Famennian synangia especially in Placotheca does not support the current understanding that the earliest pollen organs closely resembled the fructifications of the ancestral progymnosperms. Placotheca indicates earlier diversification of pollen organs than previously expected and is highly derived among the early pollen organs with trilete prepollen. It is suggested that, immediately after the origination of seed plants, pollen organs had evolved at a rapid rate, whereas their prepollen remained primitively spore-like.
authors.affiliation: Key Laboratory of Orogenic Belts and Crustal Evolution, Department of Geology, Peking University, Beijing 100871, China.
authors.forename: Deming
authors.initials: D
authors.lastname: Wang
authors.affiliation: Key Laboratory of Orogenic Belts and Crustal Evolution, Department of Geology, Peking University, Beijing 100871, China.
authors.forename: Le
authors.initials: L
authors.lastname: Liu
authors.affiliation: Department of Geology, Yunnan University, Kunming 650091, Yunnan Province, China.
authors.forename: Yun
authors.initials: Y
authors.lastname: Guo
authors.affiliation: Key Laboratory of Orogenic Belts and Crustal Evolution, Department of Geology, Peking University, Beijing 100871, China.
authors.forename: Jinzhuang
authors.initials: J
authors.lastname: Xue
authors.affiliation: Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China.
authors.forename: Meicen
authors.initials: M
authors.lastname: Meng
mesh_terms: D005075:Biological Evolution; D002681:China; D005298:Fertility / Q000235:genetics*; D011058:Pollen / Q000235:genetics*; D012639:Seeds / Q000235:genetics*