Fruit and seed structure in the ANA-grade angiosperms: Ancestral traits and specializations.

PREMISE: The representatives of the ANA-grade angiosperms demonstrate a diverse pattern of morphological characters, but their apocarpous gynoecium (except in Nymphaeaceae), composed of at least partly ascidiate carpels, the four-nucleate and four-celled female gametophyte, and the diploid endosperm (except in Amborella) are inferred to be plesiomorphies. Since the structure of fruits in Austrobaileyales is under-investigated, this research aims to fill this gap in these data, describing the carpological characters of ANA-grade taxa, and potentially illuminating the ancestral fruit and seed types of angiosperms. METHODS: The pericarp and seed coat anatomy was studied with light microscopy. The character optimization was carried out using WinClada software. RESULTS: The fruits of Austrobaileya, Trimenia, Kadsura, and Schisandra are determined to be apocarpous berries of the Schisandra type, with a parenchymatous pericarp and mesotestal (Austrobaileya) or exomesotestal seeds (other genera). Most inferred scenarios of fruit evolution indicate that the apocarpous berry is either the most probable plesiomorphic fruit type of all angiosperms, or that of all angiosperms except Amborellaceae. This inference suggests the early origin of the berry in fruit evolution. The plesiomorphic seed type of angiosperms according to reconstructed scenarios of seed type evolution was either a seed lacking a sclerenchymatous layer or an exotestal seed. CONCLUSIONS: The current research indicates that an apocarpous berry, and not a follicle, is a probable plesiomorphic character of the ANA-grade taxa and of angiosperms as a whole.

Structurally Preserved Liquidambar Infructescences, Associated Pollen, and Leaves from the Late Oligocene of the Nanning Basin, South China.

Liquidambar L. is a significant constituent of the Cenozoic flora in the Northern Hemisphere. Currently, this genus exhibits a discontinuous distribution across Asia and North America, with the center of diversity being in southeastern Asia. This study presents the first occurrence of Liquidambar in the Oligocene of South China. Fossil sweetgum infructescences, associated pollen, and leaves have been found in the Nanning Basin, Guangxi. A new species, Liquidambar nanningensis sp. nov., is described based on the morphological and anatomical characteristics of three-dimensionally preserved infructescences. The Liquidambar fossils from the Nanning Basin show a combination of features indicative of the former genera of Altingiaceae, Altingia, Liquidambar s. str., and Semiliquidambar. The new occurrence expands the taxonomic and morphological diversity of the Paleogene Liquidambar species in South China.