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 or spores (up to 7000 spores per sporangium in ) Christensenia
There are four extant eusporangiate fern families, distributed among three classes. Each family is assigned to its own order.
[1 ] [2 ]
The following diagram shows a likely
phylogenic placement of eusporangiate fern classes within the vascular plants. [3 ] [4 ]
Cladistics [ edit ]
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 polyphyletic. 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. [5 ]
Pryer & Schuettpelz, 2009
References [ edit ]
^ Alan R. Smith, Kathleen M. Pryer, Eric Schuettpelz, Petra Korall, Harald Schneider & Paul G. Wolf (2006). "A classification for extant ferns". Taxon 55 (3): 705–731. doi: 10.2307/25065646.
^ Maarten J. M. Christenhusz, Xian-Chun Zhang & Harald Schneider (2011). "A linear sequence of extant families and genera of lycophytes and ferns". Phytotaxa 19: 7–54.
^ Paul G. Wolf, Joshua P. Der, Jacob B. Davidson, Kathleen M. Pryer, Aaron M. Duffy, Amanda L. Grusz (2010). "The evolution of chloroplast genes and genomes in ferns". Plant Molecular Biology 76: 251–261. doi: 10.1007/s11103-010-9706-4.
^ a b Samuli Lehtonen (2011). "Towards Resolving the Complete Fern Tree of Life". PLoS ONE 6 (10): e24851. doi: 10.1371/journal.pone.0024851. PMC 3192703. PMID 22022365.
^ Kathleen M. Pryer, Eric Schuettpelz, Paul G. Wolf, Harald Schneider, Alan R. Smith, & Raymond Cranfill (2004). "Phylogeny and evolution of ferns (monilophytes) with a focus on the early leptosporangiate divergences". American Journal of Botany 91 (10): 1582–1598. doi: 10.3732/ajb.91.10.1582. PMID 21652310.
^ Kathleen M. Pryer & Eric Schuettpelz (2009). "Ferns". In S. Blair Hedges & Sudhir Kumar. The Timetree of Life. Oxford Biology.
^ Hardeep S. Rai & Sean W. Graham (2010). "Utility of a large, multigene plastid data set in inferring higher-order relationships in ferns and relatives (Monilophytes)". American Journal of Botany 97 (9): 1444–1456. doi: 10.3732/ajb.0900305.