Schizaeales
| Schizaeales | |
|---|---|
 |
|
| Lygodium japonicum | |
| Scientific classification | |
| Kingdom: | Plantae |
| Division: | Pteridophyta |
| Class: | Polypodiopsida/Pteridopsida (disputed) |
| Order: |
Schizaeales Schimp. |
| Families | |
Schizaeales is an order of fern (class Pteridopsida).
In the molecular phylogenetic classification of Smith et al. in 2006, the Schizaeales were placed in the leptosporangiate ferns, class Polypodiopsida. Three families, Anemiaceae, Lygodiaceae, and Schizaeaceae were recognized. The linear sequence of Christenhusz et al. (2011), intended for compatibility with the classification of Chase and Reveal (2009) which placed all land plants in Equisetopsida, reclassified Smith's Polypodiopsida as subclass Polypodiidae and placed the Schizaeales there, with the same three families. The classification of Christenhusz and Chase (2014) placed all members of the Schizaeales in a more broadly defined Schizaeaceae, reducing the three existing families to subfamilies as Anemioideae, Lygodioideae, and Schizaeoideae. The PPG I classification (2016) returned to the three-family definition of the order.
Historically, the ferns in this order were once all lumped into the family Schizaeaceae in the old order Filicales. However, although they are demonstrably related, these ferns differ markedly, and so three groups have now been elevated to family status:
At one time some workers believed the water ferns (order Salviniales) to be allied to this order because of certain structural similarities, but modern cladistic studies have ruled out any special alliance.
Schizaeales had a northern hemisphere concentration as late as the Mesozoic, but by the Quaternary, there was a clear shift to a southern hemisphere distribution
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