Phylogenetics and Taxonomy of Apocynaceae

The family Apocynaceae, comprising over 5 000 species across nearly 400 genera, exhibits striking ecological and morphological diversity, from tropical lianas and trees to temperate herbs and succulents. Classical taxonomy, founded on floral and vegetative characters, has repeatedly been challenged by morphological convergence and homoplasy. The integration of molecular phylogenetics—particularly analyses of plastid and nuclear loci—has reshaped our understanding of deep relationships, resolving tribal and subtribal lineages and redefining genera. Key clades such as the APSA assemblage (Apocynoideae, Periplocoideae, Secamonoideae and Asclepiadoideae) have been robustly supported, while paraphyletic assemblages within genera such as Hoya and Marsdenia have prompted taxonomic revision. Organellar genome studies have further unveiled plastome structural variation and mitochondrial genome expansion, informing species delimitation and DNA barcoding efforts. These advances underpin practical applications in conservation prioritisation, ornamental breeding and the exploration of medicinal compounds. Ongoing work continues to elucidate the evolutionary origins of specialised structures—such as corolline coronas, gynostegia and pollinaria—and to chart the global biogeography of this economically and ecologically significant plant family.

Research from Nature Portfolio

Recent studies have applied comparative plastome sequencing to the Hoya group, generating complete plastid genomes for twenty species. These analyses revealed one of the shortest small single-copy regions known in angiosperms and a massive expansion of inverted repeats, marked by a boundary shift from ycf1 to ndhF as a shared innovation. Phylogenomic inference based on exonic regions confirmed Papuahoya as the earliest divergent lineage and demonstrated that Hoya is paraphyletic unless Clemensiella is recognised as a separate genus. The assembly of the largest mitochondrial genome reported in the family further highlights organellar diversity and informs taxonomic decision-making within this complex clade.

Phylogenetics and Taxonomy of Apocynaceae publication trend

The graph below shows the total number of articles in phylogenetics and taxonomy of apocynaceae across all publications each year (not limited to Nature Index journals).

Technical terms

Plastome: the complete DNA sequence of a plant plastid (chloroplast) genome.

Inverted repeat: two identical sequences in reverse orientation that separate large and small single-copy regions of a plastome.

Monophyletic: a group containing an ancestor and all of its descendants.

Paraphyletic: a group containing an ancestor and only some of its descendants.

Molecular marker: a specific DNA region used to distinguish taxa and infer evolutionary relationships.

Gynostegium: a specialised floral structure in Asclepiadoideae formed by the fusion of staminal and corolla tissues.

References

1. Plastome evolution and organisation in the Hoya group (Apocynaceae). Scientific Reports (2021).
2. Evolution on the backbone: Apocynaceae phylogenomics and new perspectives on growth forms, flowers, and fruits. American Journal of Botany (2018).
3. Phylogeny of Marsdenieae (Apocynaceae, Asclepiadoideae) based on chloroplast and nuclear loci, with a conspectus of the genera. Taxon (2022).
4. Analysis of the Complete Plastomes of 31 Species of Hoya Group: Insights Into Their Comparative Genomics and Phylogenetic Relationships. Frontiers in Plant Science (2022).