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How are lycophytes classified by the Pteridophyte Phylogeny Group?
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Lower vascular plant
Aleutian maidenhair fern (Adiantum aleuticum) of the Pacific Northwest.
Under the Pteridophyte Phylogeny Group (PPG I) system published in 2016, lycophytes are classified within the class Lycopodiopsida. This system recognizes three extant orders of vascular plants:12
- Lycopodiales: Commonly known as club mosses, this order includes 16 living genera characterized by primary growth only and homosporous reproduction.32
- Selaginellales: Known as spike mosses, these plants exhibit primary growth and are heterosporous, with the genus Selaginella being the only living representative.3
- Isoetales: Comprising quillworts and their allies, these plants are heterosporous and capable of secondary growth.3
In addition to these extant groups, the broader classification of Lycopodiopsida historically includes several extinct orders known from the fossil record, such as the herbaceous Protolepidodendrales, the tree-like Lepidodendrales, and the unbranched Pleuromeiales.3