PHjakaumia

PHjakaumia is a genus of extinct flowering plants known from fossil material that includes leaf impressions and pollen grains. It is considered monotypic, containing the species PHjakaumia mirabilis. The genus is documented from Paleogene assemblages in North America and Europe, with material dating to the early to middle Eocene. The etymology of the name is not clearly recorded in primary literature, and it is treated as a constructed taxon name.

Discovery and naming of PHjakaumia occurred within the context of studies on Eocene floras, where distinctive leaf and pollen features led researchers to recognize a separate lineage. The type species, PHjakaumia mirabilis, was established based on combination of vegetative and reproductive characteristics that set it apart from related genera. Because the original description predates widespread molecular data, the placement relies on morphology and pollen ultrastructure.

Morphology is typical for a small, herbaceous to subshrubs-like plant. Leaves are palmately to deeply lobed, approximately 3–6 cm across, with serrated margins and a distinctive reticulate venation. The inflorescences carry small flowers with five petals. The fruit is described as a dry capsule. Pollen grains are triporate with a coarse exine sculpture, a feature used to diagnose the genus and distinguish it from neighboring taxa.

Distribution and ecology indicate that PHjakaumia inhabited temperate to subtropical forest ecosystems of the early Eocene, with fossil finds across North America and Europe. The plants likely occupied understory or edge habitats, contributing to the diversity of early angiosperm assemblages and providing insight into paleoenvironments of their time.

Taxonomy and research status remains unsettled. Some classifications have proposed a separate family, PHjakaumiaceae, for the genus, while others place it as incertae sedis within the angiosperms. Further fossil material and comparative studies are needed to clarify its phylogenetic position.