Happy to announce the publication of a recent collaboration with Ratidzayi Takawira-Nyenya and colleagues on the phylogeny and taxonomy of the dracaenoid genera (Sansevieria and Dracaena). The dracaenoids have significant cultural and medicinal value, but are mostly known for their widespread horticultural use (e.g., lucky bamboo, corn plant, mother-in-laws tongue/snake plant).
The dracaenoids have long been closely associated with one another, but were kept distinct based primarily on growth form. Species of Dracaena are mostly shrub and tree-like (including the famed Dragon’s Blood Trees), while Sansevieria are herbaceous drought-tolerant geophytes, frequently with cylindrical or succulent leaves.
The relationships within the dracaenoid genera are poorly known, and the recognition of Sansevieria as distinct from Dracaena has often been questioned. Using molecular phylogenetics, we aimed to resolve the phylogeny of this group, and test recently proposed infra-generic classifications.
Our main conclusions are that Sansevieria is mostly monophyletic (excluding the unusual Madagascan endemic S. sambiranensis) and embedded within Dracaena. Our phylogeny recovered weakly supported conflicts between nDNA and cpDNA datasets, but identified 4-5 geographically relevant subclades within each genus. None of the previously proposed infra-generic classifications were supported, suggesting future phylogenetic research and taxonomic revisions are needed.
Our paper also includes a detailed discussion of the taxonomic history of the dracaenoids. Despite the long-standing tradition of recognizing two genera, we found there is insufficient morphological and phylogenetic evidence to maintain them as distinct. As such, we support the synonymization of Sansevieria within Dracaena.
Regrettably, the GLOVAP paper was published while our article was under review, effectively scooping the taxonomic changes. Although disappointing to cut out most of the taxonomy, our article provides needed context and commentary and lays a foundation for future phylogenetic and taxonomic work in the dracaenoids.
Citation: R Takawira-Nyenya*, L Mucina, WM Cardinal-McTeague, KR Thiele. 2018. Sansevieria (Asparagaceae, Nolinoideae) is a herbaceous clade within Dracaena: Inference from non-coding plastid and nuclear DNA sequence data. Phytotaxa 376: 254–276. (http://dx.doi.org/10.11646/phytotaxa.376.6.2) *author for correspondence
Dr. Warren Cardinal-McTeague 