Trimeriantha X.-T.Wu, Balthazar, Grímsson, S.Ulrich, López Martínez, Heřmanová, J.Kvaček et Schönenb.

Plant Fossil Names Registry Number: PFN003489

Act LSID: urn:lsid:plantfossilnames.org:act:3489

Authors: X. Wu, M. von Balthazar, F. Grímsson, S. Ulrich, A. López Martínez, Z. Heřmanová, J. Kvaček & J. Schönenberger

Rank: genus

Reference for this name: Wu, X., von Balthazar, M., Grímsson, F., Ulrich, S., López Martínez, A., Heřmanová, Z., Kvaček, J. & Schönenberger, J. (2026): Trimerous flowers with a unique set of flower and pollen traits from the Late Cretaceous of Southern Bohemia (Czech Republic). – New Phytologist 251(4): 2266–2283.

Original diagnosis/description

Flowers pedicellate, actinomorphic, whorled, trimerous, and generally structurally and functionally bisexual. Perianth one-whorled, undifferentiated, composed of three free, broadly triangular and broadly attached tepals with valvate aestivation. Androecium of three stamen whorls with stamens of the outermost whorl in alternitepalous position and those of the two inner whorls in antetepalous position. Alternitepalous stamens attached to the dorsal, free (superior) portion of the carpels; stamens with filaments, anthers basifixed, dithecate, tetrasporangiate, with flap-valvate dehiscence. Each pollen sac with a single, spherical pollen polyad composed of 32 pollen grains. Gynoecium tricarpellate-syncarpous, with a partly inferior ovary. Short styles and stigmas free. Stigmas arranged in close proximity to each other, producing secretion at anthesis and forming an extragynoecial compitum. Ovary trilocular, with axile placentae, at least three ovules per locule.

Etymology

The genus name Trimeriantha refers to the fact that the flowers (anthos = flower in Greek) are entirely trimerous in the perianth, the androecium, and the gynoecium.