Botany Photo of the Day

Thanks again to Connor Fitzpatrick for today's write-up.

The passionflower is no stranger to Botany Photo of the Day. Daniel has already featured the genus Passiflora multiple times, writing on the fruit and the taxonomy of certain species (see Passiflora caerulea, Passiflora miniata, Passiflora alata, and Passiflora lutea).

Today's originally unidentified passionflower seems to look very much like Passiflora 'Coral Sea' (link to commercial site), so that's what we're calling it tentatively. 'Coral Sea', of course, refers to its brilliant pinky-red colour.

The genus Passiflora contains a high degree of variation in terms of flower morphology (as seen in previous BPotD posts), fruit, and vegetative features. The wide spectrum of these traits has led to a taxonomic nightmare in which the genus has been divided into 22 subgenera, and then further divided into sections, supersections, subsections, and series. The current taxonomy, set forth in 1938, is troublesome because at least 120 new species have been found / named since, and their placement into taxa has been somewhat improvised (from Phylogenetic relationships and chromosome number evolution in Passiflora). This article provides an analysis of the current taxonomic system of Passiflora based on chromosome number and chloroplast DNA. Atie et al. found that both of these features yield monophyletic groups and suggest a revision of the current taxonomy.

Bonatton et al. (A first molecular phylogenetic analysis of Passiflora - PDF) conducted a simliar study using molecular genetics to clarify the relationships within Passiflora, and to verify the legitimacy of the whole genus as a monophyletic group. Their findings, though inconsistent with the previous system, present a new taxonomy within Passiflora. Due to the incomplete sampling of all the subgenera and possibly an inadequate amount of genetic sequence data, Benatto et al. insist that more research must take place to answer the questions they originally set forth.

A great overview of the taxonomic history of Passiflora can be read via the Missouri Botanical Garden's Passiflora Research Network. If you're keen on more photographs, visit Passiflora Online.

The photograph and artwork were created by stanflouride@Flickr, aka Stannous F, a frequent commenter on BPotD and provider of interesting plant news stories. Thank you!