equisetifolia

Equisetifolia is a botanical Latin epithet meaning "having leaves like Equisetum (horsetail)." In binomial nomenclature, equisetifolia is used to describe species whose foliage or leaf arrangement resembles the horsetail genus Equisetum. The epithet is employed across several plant genera, indicating a similarity in leaf morphology rather than implying close genetic relatedness.

One widely cited example is Casuarina equisetifolia, commonly known as the Australian pine. This evergreen tree is native to coastal regions of eastern Australia and parts of Southeast Asia and has been widely planted in tropical coastal areas. Its foliage consists of slender, jointed branchlets with scale-like leaves, creating a horsetail-like appearance. The actual leaves are reduced to small scales, and photosynthesis mainly occurs in the green branchlets. The epithet reflects appearance rather than phylogeny, as Casuarina belongs to the Casuarinaceae and Equisetum to the Equisetaceae.

Equisetifolia serves as a descriptive epithet rather than a standalone taxon, and its use highlights how morphology, such as leaf form, can influence species naming across diverse plant groups.