Taxodioideae

Taxodioideae is a subfamily of conifers within the family Cupressaceae. In modern classifications, such as APG IV, Taxodioideae encompasses several living genera that share a paleoecology of wet or swampy habitats and a long fossil history. The living members typically placed in this subfamily are Taxodium, Glyptostrobus, and Metasequoia.

The genus Taxodium includes more familiar deciduous swamp trees, notably Taxodium distichum, the bald cypress, and Taxodium mucronatum, the Montezuma cypress. Glyptostrobus contains the swamp cypress, Glyptostrobus pensilis, native to parts of East Asia. Metasequoia includes the dawn redwood, Metasequoia glyptostroboides, a once-thought-extinct genus that was rediscovered in China in the 1940s. These genera are united by shared features in the Cupressaceae lineage and a history that extends back to the Mesozoic.

Ecology and morphology within Taxodioideae are characterized by adaptations to moist environments, with trees often growing in riverine or swampy settings. Foliage and cone structure vary among genera, but all produce woody cones and seeds adapted to wind dispersal. The group shows considerable evolutionary longevity, with a fossil record that helps illuminate the diversification of Cupressaceae in temperate and subtropical wetlands.

Taxonomy and circumscription of Taxodioideae have varied over time. In older classifications, related genera were placed within the separate family Taxodiaceae; in APG-based systems, they are treated as a subfamily within Cupressaceae, reflecting revised understandings of evolutionary relationships among conifers.