Macro- and micromorphological characterization of staminodes in the Plains Prickly Pear Opuntia polyacantha Haw. (Cactaceae)

Staminodes are floral structures occurring in approximately one-third of the angiosperms. These organs often go unnoticed in nature because they may mimic other floral parts. Consequently, their macro- and micromorphological portrayal in the literature is limited. This study presents a detailed desc...

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Veröffentlicht in:Brazilian Journal of Botany 2022-06, Vol.45 (2), p.665-678
Hauptverfasser: Rice, Ryan S., Vera-Vélez, Roy, Falconer, Denver J., Belliveau, Nicholas A., Cota-Sánchez, J. Hugo
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Sprache:eng
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Zusammenfassung:Staminodes are floral structures occurring in approximately one-third of the angiosperms. These organs often go unnoticed in nature because they may mimic other floral parts. Consequently, their macro- and micromorphological portrayal in the literature is limited. This study presents a detailed descriptive account of staminodes in the Cactaceae, specifically the Plains Prickly Pear, Opuntia polyacantha Haw., a species with both regular (lacking staminodes) and staminodial flowers. We present the first morphological overview of staminodes in the Cactaceae, rendering a wider perception of the variability in patterns of floral parts in this plant group. Light and scanning electron microscopy revealed that staminodes are complex parts located in the middle and outer androecial whorls and display a wide diversity of shapes and sizes. These staminodes (resembling either stamens or tepals) are considered transitional organs deriving from fertile stamens along the androecial margins via a series of transformations involving gradual widening and amalgamation with tepals. Unlike the typical dysfunctional angiosperm staminodes, pollen viability counts showed that some O. polyacantha staminodes produce fertile pollen similar in shape and size to regular stamens. The staminodes boost an increase in floral size and diameter in relation to non-staminodial flowers. Thus, larger flower diameter and landing platform combined with added viable pollen from staminodes promote visual attraction for pollinators and reproductive assurance. Because of the presence of fertile pollen, broadening the meaning of the term staminode is discussed along with the putative origin of these appendages.
ISSN:1806-9959
0100-8404
1806-9959
DOI:10.1007/s40415-022-00790-8