Trioecy in <i>Ranunculus auricomus</i> (Ranunculaceae)

Trioecy is here described for the first time in the perennial herbaceous polycarpic Ranunculus auricomus L. (goldilocks buttercup) in the Moscow Region. The study has shown that R. auricomus produces three types of flowers, differing in the structure of both the androecium and gynoecium: perfect flowers (with fertile stamens and carpels), pistillate flowers (complete absence of stamens), and staminate flowers (with fertile stamens and reduced nonfunctional carpels). The perfect flowers and their parts are larger than those of the staminate and pistillate flowers. The seven studied populations included five types of plants, forming: 1) perfect flowers (76.9–80.8% of the total number of generative plants); 2) staminate flowers (2.8–3.9%); 3) pistillate flowers (1.0–3.9%); 4) perfect and staminate flowers (10.8–15.9%); 5) perfect and pistillate flowers (1.0–3.0%). Over the five years of observations (2019–2023), plants of different sexual forms did not change the sex of flowers, and the sex ratio in the populations remained stable, with minor fluctuations.