Sequoioideae, commonly referred to as redwoods, is a subfamily of coniferous trees within the family Cupressaceae, that range in the northern hemisphere.

[5][7][8] However, Yang et al. went on to investigate the origin of a peculiar genetic component in Sequoioideae, the polyploidy of Sequoia—and generated a notable exception that calls into question the specifics of this relative consensus.

[7] A 2006 paper based on non-molecular evidence suggested the following relationship among extant species:[9] M. glyptostroboides (dawn redwood) S. sempervirens (coast redwood) S. giganteum (giant sequoia) Taxodioideae A 2021 study using molecular evidence found the same relationships among Sequoioideae species, but found Sequoioideae to be the sister group to the Athrotaxidoideae (a superfamily presently known only from Tasmania) rather than to Taxodioideae.

To investigate the origins of this polyploidy Yang et al. used two single copy nuclear genes, LFY and NLY, to generate phylogenetic trees.

[14] The fossil record shows a massive expansion of range in the Cretaceous and dominance of the Arcto-Tertiary Geoflora, especially in northern latitudes.

[15] A general cooling trend beginning in the late Eocene and Oligocene reduced the northern ranges of the Sequoioideae, as did subsequent ice ages.

The extinct genus Austrosequoia, known from the Late Cretaceous-Oligocene of the Southern Hemisphere, including Australia and New Zealand, has been suggested as a member of the subfamily.