Keelearengaceae

Keelearengaceae is a small family of flowering plants comprising a single genus, Keelearenga, and four described species. The family was proposed to accommodate a distinctive set of floral traits that did not comfortably fit within existing families, and its precise placement within the angiosperm phylogeny remains unsettled. In some contemporary classifications it is treated as a distinct lineage within the core eudicots; in others it is treated as a subfamily or tribal group of a larger family pending further molecular data.

Description: Keelearenga plants are woody shrubs or small trees, typically 2–6 meters tall. Leaves are alternate, simple, elliptic to oblanceolate with entire margins. The inflorescences are terminal panicles bearing small, bisexual flowers. Flowers show pentamerous composition with five sepals, five petals, and a typically 10-stamen androecium; the bicarpellate ovary matures into a dehiscent capsule. Seed dispersal may involve wind because seeds often have a wing-like structure.

Distribution and habitat: Endemic to tropical montane forests of Southeast Asia and nearby regions, with most species occurring above 1000 meters. They prefer shaded understory microhabitats and are often found on ridges and slopes with well-drained soils.

Genera and species: Keelearenga is the sole genus, with four described species: Keelearenga alba, Keelearenga rubra, Keelearenga longifolia, and Keelearenga vera. Nomenclature honors botanists Keelear and Rang in this account.

Conservation and significance: All species have restricted ranges, and habitat loss threatens several populations. Keelearengaceae is of interest to researchers studying early-diverging lineages of core eudicots and contributes to understanding tropical plant diversity.