The name Glyptostrobus comes from Greek, meaning ‘carved cone’ (Eckenwalder 2009; Veitch 1881). Although the genus was first described in 1847 its name is more likely to invoke thoughts of Metasequoia glyptostroboides, a tree named for its resemblance to Glyptostrobus in 1948 and which quickly went on to become a dendrological superstar, quite at odds with its namesake. Another comparison worth making is with Cryptomeria (‘hidden parts’) whose name refers to the fused but distinguishable, pointed lobes of the seed scale, a feature shared by Glyptostrobus (Rushforth 1987; Eckenwalder 2009). In fact, etymology aside, Cryptomeria and Taxodium are probably Glyptostrobus’s closest relatives, forming a clade in the now obsolete Taxodiaceae (Schulz & Stützel 2007).
Given the diversity of leaf morphology it displays, it is unsurprising that in the 230 or more years since its discovery for modern botany, Glyptostrobus has been classified as a member of Cupressus, Thuja, Juniperus, and most commonly Taxodium (Farjon 2005). With its single living species the taxonomic history of the genus represents more a story of lateral reclassification than discovery or splitting, as botanists tried to find the best way to classify the odd combination of characters that this botanical platypus presents.
Indeed, Glyptostrobus is only likely to be confused with members of Taxodium, its ecological equivalent in North America (Averyanov et al. 2009). Like the related genera Taxodium and Metasequioia, the branchlet system is dimorphic, divided into branchlets with needle-like leaves which are shed annually as units, and more persistent, slender branchlets with scale-like foliage. While these genera share a disordered crown structure and deciduous habit, they differ in a number of details. The branchlets of Glyptostrobus remain green for several years, while in Metasequoia and Taxodium they become brown in their second year. Glyptostrobus seed cones differ strikingly from those of Taxodium: rather than the ‘football-like’ structure of adnate, peltate scales of Taxodium, the cone of Glyptostrobus is formed of a cluster of closely fitting and faceted scales that are delicately attached to a squat rachis at their bases. The long, scaly stalks of the cones are also distinct (Henry & McIntyre 1926).