Eusporangiate fern
Common name for a group of ferns
From Wikipedia, the free encyclopedia
Eusporangiate ferns are vascular spore plants, whose sporangia arise from several epidermal cells and not from a single cell as in leptosporangiate ferns. Typically these ferns have reduced root systems and sporangia that produce large amounts of spores (up to 7000 spores per sporangium in Christensenia).
| Eusporangiate fern | |
|---|---|
| |
| Botrychium lunaria | |
Scientific classification | |
| Kingdom: | Plantae |
| Clade: | Embryophytes |
| Clade: | Tracheophytes |
| Division: | Polypodiophyta |
| Class: | Polypodiopsida |
| Groups included | |
| Excluded | |
There are four extant eusporangiate fern families, distributed among three classes. Each family is assigned to its own order.[1][2]
- Class Psilotopsida
- Order Psilotales, family Psilotaceae – Whisk ferns (2 genera, about 17 species)
- Order Ophioglossales, family Ophioglossaceae – Adder's-tongues (5 genera, about 80 species)
- Class Equisetopsida
- Order Equisetales, family Equisetaceae – Horsetails (1 genus, about 15 species)
- Class Marattiopsida
- Order Marattiales, family Marattiaceae – Marattoid ferns (6 genera, about 500 species)
The following diagram shows a likely phylogenic placement of eusporangiate fern classes within the vascular plants.[3][4]
|
eusporangiate
ferns |
Cladistics
While it is generally accepted that the leptosporangiate ferns are monophyletic, it is considered to be likely that the eusporangiate ferns, as a group, are paraphyletic.[5] In each of the three examples from recently published studies, shown in the following table, it can be seen that, together, the four eusporangiate fern families do not form a single clade.