The reproductive multiverse of diandrous orchids: two anthers offer new perspectives on the role of floral traits.

Authors

João C F Cardoso, Paulo E Oliveira, Zong-Xin Ren, Carlos A Matallana-Puerto

Published in

Annals of botany. Aug 23, 2026. Epub Aug 23, 2026.

Abstract

Floral trait influences on pollination performance have been extensively studied in monandrous orchids (one anther). Diandrous orchids (two anthers) introduce a new hierarchical level because removing two pollen smears requires at least two visits, potentially indicating more attractive flowers and greater opportunities for pollination performance via male function. We studied trait-performance relationships in diandrous orchids using a threatened hoverfly-pollinated Phragmipedium that mimics oviposition sites by resembling aphids.
We measured flower size and height and quantified male and female performances (i.e., pollen smear removal and deposition) across two flowering seasons. Because the influence of different traits is not always independent in trait-performance relationships, we applied commonality analyses to decompose the unique and shared explained variances of traits.
Larger and taller flowers exhibited higher male and female performances, suggesting positive pollinator-mediated selection. This pattern remained consistent when performance types were combined, particularly for flowers with two removals and one deposition (2♂/1♀), representing the maximum performance. Although individual trait effects explained more variance, reaching up to 15% as in the case of flower height on female performance, the combined effects of flower size and height were also relevant, reaching up to 6% as in the case of 1♂/1♀ performance. This indicates that even non-correlated traits can have a shared effect.
Despite oviposition-site mimicry being widespread in angiosperms, this is the first investigation on the effects of floral trait variation on performance in this system, corroborating general patterns observed in other rewarding and non-rewarding systems. We also demonstrate positive effects of attractive traits in diandrous orchids when male and female functions are considered separately and jointly, especially in the maximum performance type (2♂/1♀), corroborating theoretical predictions for this system where two anthers are an additional level of complexity.

PMID:
42633706
Bibliographic data and abstract were imported from PubMed on 24 Aug 2026.

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