Browsing through the November BPotD entries, I noticed an overall palette of muted, autumnal colours for the month. Time to brighten things up!
Gazania contains a number of species and cultivars important in horticulture, including Gazania rigens (or the treasure flower). The diversity of inflorescence colour within and between species (e.g., an image search for Gazania rigens) and other morphological characteristics provoked a re-examination of what was once thought to be a group of sixteen southern African species. In Globally grown, but poorly known: species limits and biogeography of Gazania Gaertn. (Asteraceae) inferred from chloroplast and nuclear DNA sequence data, the authors published the results of their research into the molecular relationships of 15 of the (formerly) 16 species. Of the 15 species they studied, they determined that 7 are monophyletic (and therefore it makes sense to keep these distinct). The other 8 species formed an interbreeding species complex, known as the K-R clade (for Gazania krebsiana and Gazania rigens, the two most prominent “species” within the complex). If this sounds familiar to you, perhaps it is because I wrote a very similar entry for Gazania krebsiana six years ago, citing the same paper!
Given the results of the study, should one continue to recognize entities such as Gazania krebsiana and Gazania rigens? Whenever I encounter such species complexes in the wild (*cough* Castilleja), I use the lingo I’ve learned from others: making the distinction between “good” (implying close to the definitive version of what that species looks like, perhaps in previous publications) versus “muddy” (one where intermediate characteristics between two or more “good” species is prominent). As mentioned in the Gazania krebsiana entry, biological reality resists the tidy boxes people prefer to use to communicate. Perhaps we need a better lexicon to deal with these instances; “good” and “muddy” don’t really cut it, in part because of the judgmental nature of the terms.
Gazania was named in honour of Theodorus Gaza, “translator of Aristotle, [and] one of the Greek scholars who were the leaders of the revival of learning in the 15th century”. It is coincidental, perhaps, that a genus exemplifying the need for better clarity in taxonomic language is named after someone who was well-respected for the precision and accuracy of his translations.