Classen-Bockhoff, RegineCelep, FerhatAjani, YousefFrenken, LisaReuther, KerstinDogan, Musa2025-01-212025-01-2120232041-2851https://doi.org/10.1093/aobpla/plad065https://hdl.handle.net/20.500.12587/24441The wild carrot (Daucus carota) is famous for its dark flowers in the umbel centre. Several studies have been conducted to figure out their functional significance, but the evolution of the dark centre remains an enigma. In the present paper, we consider all known apioid species with dark-centred umbels to get a deeper understanding of their biology and evolution. Based on herbaria studies, literature and field work, we reconstructed the distribution area of 10 species (7 genera, 6 clades) of Apiaceae-Apioideae. To recognize homology of the dark structures, developmental studies were conducted in Artedia squamata and Echiophora trichophylla Field studies included architecture, flower morph distribution (andromonoecy) and flowering sequence within the plants, abundancy and behaviour of umbel visitors and preliminary manipulation experiments (removal/adding of dark structures). The dark structures are not homologous to each other. In the Daucus alliance, central flowers or umbellets are conspicuous, whereas in other species dark brush-like (A. squamata) or club-shaped structures (Dicyclophora persica, Echinophora trichophylla, Tordylium aegyptiacum, T. cappadocicum) develop from a naked receptacle. Species are andromonoecious, have a modular architecture and flower in multicyclic protandrous sequence. Among the many umbel visitors, beetles were the most abundant group. Only visitors found on umbels in both flowering phases were recognized as possible pollinators. Manipulation experiments indicated that the dark structures influence the behaviour of some, but not all umbel visitors. In Echinophora trichophylla, a massive gall infection was observed. It is evident that the dark structures evolved several times in parallel. The brush- and club-shaped structures are interpreted as the results of mutations affecting umbel development. Dark umbel centres are most likely stabilized by selection due to their general adaptive function. Their appearance in an area known as a hotspot of beetle pollination gives rise to the assumption that they may act as beetle marks. The wild carrot is famous for its red flower in the umbel centre. The function of this flower has been discussed since the time of Darwin. Experiments have led to the general conclusion that it is adaptive addressing at least part of the unspecialized visitors and pollinators. We show that Daucus carota is not the only species with dark umbel-centres. At least 10 apioid species from 7 genera and 6 clades have conspicuous dark structures in their umbels. It is evident that the morphologically diverse structures evolved in parallel. Some receptacle structures appear to be inherited mutations linked with the peculiarities of the umbel meristem. As the diversity centre of the species with dark-centred umbels is SW Asia, an area known as a hotspot of beetle pollination, we speculate that the dark umbel centres may act as beetle marks not only but primarily attracting beetles as pollinators.eninfo:eu-repo/semantics/openAccessAnatolia; Artedia squamata; beetle marks; dark-centred umbels; Daucus alliance; Echinophora trichophylla; floral unit meristem; generalized pollination; homology; multicyclic protandry; mutation; umbel developmentArticle15510.1093/aobpla/plad06537908286WOS:001109059000009Q2