Floral structure and ontogeny of Syndiclis (Lauraceae)

A new species of Cinnamomum (Lauraceae) from southwestern China

Field investigations in Guizhou, China, in 2020 resulted in the discovery of an unknown species of Lauraceae. Morphological studies revealed that it is a new species of CinnamomumSchaeff.sect.Camphora Meisn., based on the large terminal buds, and alternate leaves with pinnate veins. It is distinguished from other species of sect. Camphora by the rather large perulate terminal buds with numerous bracts, larger flowers, oblong-elliptic linear tepals twice as long as the stamens, and the deep cup-shaped fruiting cupule. It is here described and illustrated as a new species, Cinnamomumguizhouense C.Y.Deng, Zhi Yang et Y.Yang. A key to distinguish it from related species in the same area is provided. In addition, we list the new species as Critically Endangered (CR), and suggest to conduct ex situ conservation, collect seeds and plant the species in botanic gardens.

Dancing on the platform: Lability of floral organs of Beilschmiedia appendiculata (Lauraceae)

Floral characters are important for the systematics of the Lauraceae. However, structure and development of the flowers remain poorly known in the family. In this study, we observed the variation and early development of flowers of Beilschmiedia appendiculata, which belongs to the Cryptocarya clade of the family. The results indicate that the shoot apical meristems (SAMs) of the floral buds are enlarged and become a platform for the programmed initiation of the floral organs; floral organs develop basically in an acropetal pattern; phyllotaxis is whorled, initiation of floral primordia within a whorl is asynchronous; floral merosity is extremely variable, for example, dimerous, trimerous, tetramerous, dimerous plus trimerous, and trimerous plus tetramerous. In addition, this species has lost the innermost staminal whorl and glands are not closely associated with stamens of the third staminal whorl, which is unusual in the family Lauraceae. Our new observations broaden our knowledge of the variation of floral structure in Beilschmiedia and pose a fundamental question regarding the ecology underlying the lability of floral organs in B. appendiculata.

Plastome phylogenomics, systematics, and divergence time estimation of the Beilschmiedia group (Lauraceae)

Intergeneric relationships of the Beilschmiedia group (Lauraceae) remain unresolved, hindering our understanding of their classification and evolutionary diversification. To remedy this, we sequenced and assembled complete plastid genomes (plastomes) from 25 species representing five genera spanning most major clades of Beilschmiedia and close relatives. Our inferred phylogeny is robust and includes two major clades. The first includes a monophyletic Endiandra nested within a paraphyletic Australasian Beilschmiedia group. The second includes (i) a subclade of African Beilschmiedia plus Malagasy Potameia, (ii) a subclade of Asian species including Syndiclis and Sinopora, (iii) the lone Neotropical species B. immersinervis, (iv) a subclade of core Asian Beilschmiedia, sister to the Neotropical species B. brenesii, and v) two Asian species including B. turbinata and B. glauca. The rampant non-monophyly of Beilschmiedia we identify necessitates a major taxonomic realignment of the genus, including but not limited to the mergers of Brassiodendron and Sinopora into the genera Endiandra and Syndiclis, respectively. Along these lines, the high degree of continental, clade-wide endemism we identify suggests that geographical distribution may be a good proxy for delineating taxa within this group. Our molecular divergence time estimates indicate that stem Beilschmiedia group members date to the Early Eocene (~50 Ma); their crown age dates to the Eocene-Oligocene boundary (~34 Ma). These findings contradict older estimates of the group and support mounting evidence that the origin and diversification of many pantropical angiosperm clades are not easily attributed to strict western Gondwanan vicariance. Finally, our study highlights the phylogenetic utility of plastomes in Lauraceace, and lays a solid foundation for future phylogenomic and biogeographic investigations within the family.