Between wind and visitors? Insights into floral anatomy, taxonomy, and reproductive biology in Cryptangieae (Cyperaceae)

Abstract Background and Aims The flowers of Cyperaceae, especially in Cyperoideae, have two whorls of perianth (sometimes absent), three stamens, and a tricarpellate syncarpous gynoecium. The family is traditionally described as anemophilous, but reports of ambophily, entomophily, and hydrophily have been documented. Cryptangieae stands out for its unisexual spikelets, reddish stigmas, and occasionally reddish stamens, potentially attracting pollinators. Despite these distinctive features, floral anatomy and its taxonomic and pollination implications remain insufficiently investigated in this tribe. Methods We conducted a comparative analysis of floral anatomy in species of Cephalocarpus, Cryptangium, Lagenocarpus, and Krenakia. We also carried out field observations in Lavras and at the Serra do Cipó National Park (Minas Gerais, Brazil) to record floral visitors and assess their behavior. Scanning electron microscopy was employed to examine pollen adhesion to visitors’ exoskeletons. Key Results Unisexual flowers follow a basipetal development pattern in the spikelets, with ovaries exhibiting a “cyperoid organization”. Some species may possess secretory structures in different regions of the pistil; however, these are not consistently present among individuals, and their taxonomic significance remains uncertain. Notably, the coloration of stigmas and stamens, as well as the possible secretory structures, may function as attractants for floral visitors, such as ants (Formicidae), spiders (Thomisidae), and ladybugs (Coccinellidae). The behavior of these animals was consistent with the role of occasional pollinators, with ladybugs carrying the highest number of pollen grains. Conclusions Cryptangieae show distinctive floral and ecological traits, particularly in the anther epidermis, connective crest, the color and number of stamens and stigmas, pistil secretory structures, and the presence of a gynophore. Although evidence suggests ambophily, wind may still play a predominant role in pollination. Further studies should clarify these mechanisms and characterize possible exudates.