Danais includes about 49 species of woody climbers found in the Western Indian Ocean region, mainly in Madagascar but also with several species also in the Mascarenes and the Comores and one more disjunct in East Africa. The genus is characterized by its climbing habit; opposite or 3-4-verticillate leaves; interpetiolar, triangular to 2-lobed, fimbriate, or erose, generally persistent stipules that are interpetiolar or in a few species fused around the stem; terminal and/or axillary, bracteate, cymose inflorescences; bisexual, distylous, small flowers with (4)5(6) calyx lobes, corolla lobes, and stamens; funnelform to salverform, often markedly slender corollas with the lobes valvate-reduplicate in bud and the tubes sometimes fenestrate at the base; 2-lobed stigmas; ovary with 2 locules and numerous ovules in each locule; capsular, loculicidal, subglobose, generally papery to somewhat woody fruits; and seeds that are characteristically flattened and winged but are angled in a few species. The plants sometimes have a foetid odor. The corollas are variously pale green, white, yellow, orange, red, violet, blue, purple, or nearly black and characteristically, the tube and abaxial surface of the lobes are are differently colored from the showy adaxial surface of the lobes. The corolla throat is usually pubescent with pilosulous to pilose trichomes, which are generally bright white. The capsules of Danais split from the top to below the middle, and the seeds are released from the open main part of the captule. Danais lyallii and Danais rhamnifolia are the most commonly collected Danais species in Madagascar, and Danais fragrans is reported to be widespread and common in Mauritius (Verdcourt et al., 1989) 

Danais is similar to Payera and Schismatoclada, and the details of the separation of these are still under study (Razafimandimbison et al, 2022; Taylor et al., 2024). Buchner & Puff (1993) stated that they distinguished Danais by its climbing habit, inflorescences that may sometimes be axillary, and loculicidal capsules that are not beaked at the apex; vs. erect trees and shrubs with terminal inflorescences and fruits that are beaked, variously loculicidal or septicidal, and often dehiscent through the beak portion of the capsule in Payera and Schismatoclada. Buchner & Puff (1993) and Puff & Buchner (1994) additionally diagnosed Danais in practice by flattened winged seeds, and excluded some species that have angled seeds. As to their formally stated characters, some are problematic (Taylor, et al., 2024). In Payera and Schismatoclada, the capsules are generally semi-inferior, and split from the top through the beak to near or below the middle of the capsule body, then the pyramidal or tubular beak portion splits again and the seeds are released often mainly through that beak portion. This was the form Buchner & Puff contrasted with Danais, with its fully inferior fruits. However, he fruits of some species of Danais are actually shortly beaked (i.e., with the top part of the fruit inside the calyx limb prolonged above the calyx limb) and the capsule is shortly semi-inferior, so this fruit character is not diagnostic for Danais, and overall, fruit form and dehiscence are not reliable diagnostic characters for any of these genera. Krüger et al. (2012) and Razafimandimbison et al. (2022) studied these three genera with molecular data, and found Danais well supported as a monophyletic lineage separate from Payera and Schizmatoclada even though the circumscriptions of the other genera are not fully resolved. They concluded that only the lianescent habit is diagnostic for Danais. 

Buchner & Puff (1993) detailed the morphology and anatomy of Danais, and Puff & Buchner (1994) presented a revision of the species found in Madagascar. As noted above, they diagnosed Danais by the combination of a climbing habit and flattened winged seeds, and they transferred some Danais species to Payera and they excluded some other species from Danais without providing another genus placement,. They also noted several other names that were unclear as to the identity of the plant. The taxonomy of Puff & Buchner is generally well supported by new collections, even though they knew many of the species only from limited and often poor material. Several of their species included an rather wide range of flower sizes, and others were based on details of the stipules that, however, can be quite variable. Some of the species as they treated them were quite variable and difficult to fully characterize morphologically (e.g., Danais cernua, Danais terminalis, Danais fragrans, Danais aurantiaca). Danais was treated in the Mascarenes by Verdcourt et al. (1989), and in East Africa by Verdcourt (1976). 

The molecular studies of Krüger et al. (2012) and Razafimandimbison et al. (2022) found Danais to be monophyletic, as noted above, but also found that several Danais species included more than one differentiated lineage. Notably, Krüger et al. (2012) concluded that Puff & Buchner's (1994) and Verdcourt et al.'s (1989) circumscription of Danais fragrans included two distinct lineages, one in Mauritius, where the type was collected, and the other in Madagascar. They treated these in their analysis as the accessions "Danais fragrans 1", from Mauritius, and "Danais fragrans 2" and "Danais fragrans 3" from Madagascar. They noted in their discussion that the Malagasy plants should be seprarated and probably correctly called Danais lyalili, but did not publish a formal taxonomic statement separating these. They did later adopt the name Danais lyallii (Razafimandimbison et al., 2022), but this name change was not formally stjudied and or given a detailed taxonomic statement there. Razafimandimbison et al. (2022) presented a new analysis with a significantly expanded species sampling of Danais. 

The taxonomy and circumscription of the species of Danais was then reviewed comprehensively by Taylor et al. (2024), clarified the identities of some mames, narrowed the circumscriptions of some species, synonymized a few species, and described some new species. They also transferred into Danais several species that were excluded by Puff & Buchner (1994), and presented an updated morphological description and a key to all the species of the genus.

Flower size and inflorescence position vary widely among Madagascar's Danais species, which are now documented by many good recent collections from new areas of Madagascar. Buchner & Puff (1993) discussed the diversification in pollination mode within the genus, which has species variously adaptated for pollination by hawkmoths, by other kinds of moths, and by a range of diurnal insects. They noted that the flowers of some species are sweetly fragrant, and others appear to have no odor. Puff & Buchner (1994) presented a graphical overview of the species by corolla and fruit sizes, and distribution maps for individual species. The corollas often have colorful lobes (red, orange, yellow, purple) but greenish white or dull white or cream tubes.They noted that some species seem to have some variation in internal corolla pubescence between the long-styled and short-styled form, but this has not been seen in the review here for species that have good specimen documentation. No field studies of pollination or other ecological aspects of Danais seem to have been conducted. 

For more detailed information on ecology and range of many of the individual species found in Madagascar, see the Madagascar Project. Razafimdimbison et al. (2022) presented a phylogram for Danais based on voucher specimens that were variously identified to species or not, and they labelled the eight terminals in their Fig. 6 that were not identified to a known species with unpublished provisional names; those names have not yet been validly published or diagnosed so their identities are not yet entirely clear. 

Author: C.M. Taylor. The content of this web page was last revised on  28 November 2024.
Taylor web page: http://www.mobot.org/MOBOT/Research/curators/taylor.shtml

Humid to wet forest at low to montane elevations; most species endemic in Magascar, several species endemic in the Mascarenes (Mauritius, Reunion, Rodrigues), two found in the Comores (one shared with Madagscar), and one species endemic in the mountains of central Tanzania.

• Buchner, R. & C. Puff. 1993. The genus complex Danais-Schismatoclada-Payera (Rubiaceae). Character states, generic delimitation and taxonomic position. Bull. Mus. Natl. Hist. Nat., B, Adansonia, sér. 4 15: 23–74.
• Puff, C. & R. Buchner. 1994. Revision of Danais Vent. (Rubiaceae) in Madagascar and the Comores. Bull. Mus. Natl. Hist. Nat., B, Adansonia, sér. 4 16: 11–64.
• Puff, C. 1991. The monotypic Malagasy genus Alleizettea is Danais volubilis (Rubiaceae). Novon 1(3): 134.
• Taylor, C. M. & Z. S. Rogers. 2013. Six new species of Danais Vent. (Rubiaceae, Danaideae) from Madagascar. Candollea 68(1): 167–180.
• Krüger, A., S. G. Razafimandimbison & B. Bremer. 2012. Molecular phylogeny of the tribe Danaideae (Rubiaceae: Rubioideae): Another example of out-of-Madagascar dispersal. Taxon 61(3): 629–636.
• Razafimandimbison, S. G., N. Wikström, A. Khodabandeh & C. Rydin. 2022. Phylogeny of the Madagascar-centered tribe Danaideae (Rubiaceae) as a precursor to txonomic revision: insights into its generic and species limits, affinities and distribution. Ann. Bot. (Oxford) 130: 849-867.
• Verdcourt, B., J.-F Leroy & D. D. Tirvengadum. 1989. 108. Rubiacées. Fl. Mascareignes 1–135.
• Verdcourt, B. 1976. Rubiaceae (part 1). 1–414. In W. B. Turrill & R. M. Polhill (eds.) Fl. Trop. E. Africa. A. A. Balkema, Rotterdam.
• Taylor, C. M., S. G. Razafimandimbison, M. W. Callmander & H. H. Schmidt. 2024. A new review of the Western Indian Ocean genus Danais (Rubiaceae: Danaideae), with seven new species from Madagascar. Candollea 79(2): 235–276.