Belongs within: Asteroideae.
The Calenduleae are a group of composite-flowered plants in which the receptacle is naked and which lack a pappus (Black & Robertson 1965).
Characters (from Black & Robertson 1965): Heads heterogamous-radiate; disk flowers usually bisexual but sterile; styles of sterile disk flowers shortly bifid or entire at summit; receptacle nake; anthers acute or acuminate at base; achenes comparatively large, variable in shape; pappus absent; leaves alternate.
<==Calenduleae BR65
|–Eriachaenium S06
|–Dimorphotheca (Vaillant) Moench. 1794 [incl. Gattenhoffia von Necker 1790 (nom. rej.)] BR65
| |–D. pluvialis [incl. D. annua] BR65
| `–D. sinuata H93
|–Calendula BR65
| |–C. arvensis BR65
| `–C. officinalis BR65
|–Chrysanthemoides Medik. 1789 BR65
| `–C. monilifera [=Osteospermum moniliferum] BR65
| |–C. m. ssp. monilifera WFS04
| `–C. m. ssp. rotundata WFS04
`–Osteospermum BR65
|–O. calendulaceum [=Oligocarpus calendulaceus] BR65
|–O. clandestinum [=Tripteris clandestina] BR65
|–O. ecklonis [=Dimorphotheca ecklonis] H93
|–O. montanum CV06
`–O. muricatum CV06
|–O. m. ssp. muricatum CV06
`–O. m. ssp. longiradiatum CV06
*Type species of generic name indicated
REFERENCES
[BR65] Black, J. M., & E. L. Robertson. 1965. Flora of South Australia. Part IV. Oleaceae–Compositae. W. L. Hawes, Government Printer: Adelaide.
[CV06] Craven, P., & P. Vorster. 2006. Patterns of plant diversity and endemism in Namibia. Bothalia 36 (2): 175–189.
[H93] Hickman, J. C. (ed.) 1993. The Jepson Manual: Higher Plants of California. University of California Press: Berkeley (California).
[S06] Stuckert, T. 1906. Distribución geográfica de la flora Argentina. Géneros de la familia de las compuestas. Anales del Museo Nacional de Buenos Aires, serie 3, 6: 303–309.
[WFS04] Winks, C. J., S. V. Fowler & L. A. Smith. 2004. Invertebrate fauna of boneseed, Chrysanthemoides monilifera ssp. monilifera (L.) T. Norl. (Asteraceae: Calenduleae), an invasive weed in New Zealand. New Zealand Entomologist 27: 61–72.