<i>Menyanthes trifoliata</i> L., a heterostyly plant, is an endangered species in Korea. Floral morphology has been published for <i>M. trifoliata</i>, but few works have concentrated on pollen dimorphism differences accompanied by floral dimorphism. Here, we conducted a comparative morphological study of two morphs to investigate a dimorphism system with Korean populations. Pollen morphological characteristics were observed with a light microscope and a scanning electron microscope. For the pin type, pollen size is 36.01 ± 2.01 µm, whereas for the thrum type it is 41.28 ± 2.58 µm in terms of the equatorial diameter. The two morphs have a small apocolpium field at 5.62 ± 0.30 for the pin type and 6.24 ± 0.70 for the thrum type. The configuration of the aperture was tricolpate with a striate ridge in the two morphs. However, they have different pollen shapes and sizes, stigma shapes, and apocolpium sizes. <i>M. trifoliata</i> only has different pollen sizes and shapes between European populations and Korean populations. Nevertheless, Korean populations also show pollen dimorphism correlated with their floral dimorphism.

The basic information of ovule and seed characteristics was investigated for five monotypic and endemic genera in the Korean peninsula as categorized by the Flora of Korea category. The carpels and seeds were sectioned with a rotary microtome. Mature seeds were coated with platinum using an ion sputter and observed using a scanning electron microscope. As a result, <i>Abeliophyllum</i> was found to be anatropous and a unitegmic ovule, with a slightly colliculate seed surface and exotestal seed coat type. The ovule of <i>Coreanomecon</i> was anatropous and bitegmic, having a distinct echinate seed surface, and exo-endotestal seed coat type with a prismatic crystal in the mesotesta. The ovule of <i>Hanabusaya</i> was anatropous and a unitegmic, with a long reticulate seed surface sculpture, and distinct exotestal seed coat type. In addition, a wing developed at the opposite side of the raphe bundle. <i>Megaleranthis</i> was an anatropous and bitegmic ovule, having a small pentagonal disk shape, a concave seed surface and exotestal seed coat type. Finally, <i>Pentactina</i> was also anatropous and a unitegmic ovule, reticulate seed sculpture, and endotestal seed coat type. These data will be proving to be a source of good information for securing bio-sovereignty in the near future.