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Generic relationships in Araliaceae: looking into the crystal ball
Abstract
Our understanding of relationships among Apiales and within Araliaceae has
progressed considerably in the last decade thanks to numerous molecular phylogenetic studies. It is now clear that traditional infrafamilial systems of classification of Araliaceae fail to reflect evolutionary relationships and
that the morphological features on which they were based exhibit high levels of
homoplasy. Recent studies have provided a very
different picture of relationships in the family, and are rapidly converging on
a consensus that allows us to review the status of the 41 genera currently recognised in Araliaceae and to
consider alternative circumscriptions for those that are not monophyletic.
Twenty-four small and medium-sized genera are unlikely to be modified, whereas
five others (Dendropanax, Oreopanax, Osmoxylon, Pseudopanax and Sinopanax) may
require changes in circumscription. The status of four other small genera is
not yet clear, but the two largest genera will require considerable
re-alignments: Polyscias
(c. 150 spp.), which is paraphyletic
with respect to six other genera, and the polyphyletic genus Schefflera (c.
650–900 spp.), which represents five geographically
distinct clades. While it is still too early to make
formal taxonomic changes to these genera, current evidence suggests that Polyscias sensu
lato will likely be
realigned into 5–8 geographically coherent genera, while Schefflera sensu
lato will be split into 10–16 genera.
South African Journal of Botany 2004, 70(3): 382–392
progressed considerably in the last decade thanks to numerous molecular phylogenetic studies. It is now clear that traditional infrafamilial systems of classification of Araliaceae fail to reflect evolutionary relationships and
that the morphological features on which they were based exhibit high levels of
homoplasy. Recent studies have provided a very
different picture of relationships in the family, and are rapidly converging on
a consensus that allows us to review the status of the 41 genera currently recognised in Araliaceae and to
consider alternative circumscriptions for those that are not monophyletic.
Twenty-four small and medium-sized genera are unlikely to be modified, whereas
five others (Dendropanax, Oreopanax, Osmoxylon, Pseudopanax and Sinopanax) may
require changes in circumscription. The status of four other small genera is
not yet clear, but the two largest genera will require considerable
re-alignments: Polyscias
(c. 150 spp.), which is paraphyletic
with respect to six other genera, and the polyphyletic genus Schefflera (c.
650–900 spp.), which represents five geographically
distinct clades. While it is still too early to make
formal taxonomic changes to these genera, current evidence suggests that Polyscias sensu
lato will likely be
realigned into 5–8 geographically coherent genera, while Schefflera sensu
lato will be split into 10–16 genera.
South African Journal of Botany 2004, 70(3): 382–392
