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16 - Fern classification
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- By Alan R. Smith, University Herbarium, University of California, Berkeley, CA 94720, USA, Kathleen M. Pryer, Department of Biology, Duke University, Durham, NC 27708, USA, Eric Schuettpelz, Department of Biology, Duke University, Durham, NC 27708, USA, Petra Korall, Department of Phanerogamic Botany, Swedish Museum of Natural History, SE-104 05 Stockholm, Sweden, Harald Schneider, Natural History Museum, Cromwell Road, London SW7 5BD, UK, Paul G. Wolf, Department of Biology, Utah State University, Logan, UT 84322, USA
- Edited by Tom A. Ranker, University of Colorado, Boulder, Christopher H. Haufler, University of Kansas
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- Book:
- Biology and Evolution of Ferns and Lycophytes
- Published online:
- 11 August 2009
- Print publication:
- 19 June 2008, pp 417-467
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Summary
Introduction and historical summary
Over the past 70 years, many fern classifications, nearly all based on morphology, most explicitly or implicitly phylogenetic, have been proposed. The most complete and commonly used classifications, some intended primarily as herbarium (filing) schemes, are summarized in Table 16.1, and include: Christensen (1938), Copeland (1947), Holttum (1947, 1949), Nayar (1970), Bierhorst (1971), Crabbe et al. (1975), Pichi Sermolli (1977), Ching (1978), Tryon and Tryon (1982), Kramer (in Kubitzki, 1990), Hennipman (1996), and Stevenson and Loconte (1996). Other classifications or trees implying relationships, some with a regional focus, include Bower (1926), Ching (1940), Dickason (1946), Wagner (1969), Tagawa and Iwatsuki (1972), Holttum (1973), and Mickel (1974). Tryon (1952) and Pichi Sermolli (1973) reviewed and reproduced many of these and still earlier classifications, and Pichi Sermolli (1970, 1981, 1982, 1986) also summarized information on family names of ferns. Smith (1996) provided a summary and discussion of recent classifications.
With the advent of cladistic methods and molecular sequencing techniques, there has been an increased interest in classifications reflecting evolutionary relationships. Phylogenetic studies robustly support a basal dichotomy within vascular plants, separating the lycophytes (less than 1% of extant vascular plants) from the euphyllophytes (Figure 16.1; Raubeson and Jansen, 1992, Kenrick and Crane, 1997; Pryer et al., 2001a, 2004a, 2004b; Qiu et al., 2006). Living euphyllophytes, in turn, comprise two major clades: spermatophytes (seed plants), which are in excess of 260000 species (Thorne, 2002; Scotland and Wortley, 2003), and ferns (sensu Pryer et al. 2004b), with about 9000 species, including horsetails, whisk ferns, and all eusporangiate and leptosporangiate ferns.
15 - Fern phylogeny
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- By Eric Schuettpelz, Department of Biology, Duke University, Durham, NC 27708, USA, Kathleen M. Pryer, Department of Biology, Duke University, Durham, NC 27708, USA
- Edited by Tom A. Ranker, University of Colorado, Boulder, Christopher H. Haufler, University of Kansas
-
- Book:
- Biology and Evolution of Ferns and Lycophytes
- Published online:
- 11 August 2009
- Print publication:
- 19 June 2008, pp 395-416
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Summary
Introduction
As a consequence of employing DNA sequence data and phylogenetic approaches, unprecedented progress has been made in recent years toward a full understanding of the fern tree of life. At the broadest level, molecular phylogenetic analyses have helped to elucidate which of the so-called “fern allies” are indeed ferns, and which are only distantly related (Nickrent et al., 2000; Pryer et al., 2001a; Wikström and Pryer, 2005; Qiu et al., 2006). Slightly more focused analyses have revealed the composition of, and relationships among, the major extant fern clades (Hasebe et al., 1995; Wolf, 1997; Pryer et al., 2004b; Schneider et al., 2004c; Schuettpelz et al., 2006; Schuettpelz and Pryer, 2007). A plethora of analyses, at an even finer scale, has uncovered some of the most detailed associations (numerous references cited below). Together, these studies have helped to answer many long-standing questions in fern systematics.
In this chapter, a brief synopsis of vascular plant relationships – as currently understood – is initially provided to place ferns within a broader phylogenetic framework. This is followed by an overview of fern phylogeny, with most attention devoted to the leptosporangiate clade that accounts for the bulk of extant fern diversity. Discussion of finer scale relationships is generally avoided; instead, the reader is directed to the relevant literature, where more detailed information can be found.