Spermatophyta

From Palaeos.org

Chlorobionta
  |--Chlorophyta
  `--Charophyta
       `--Embryophyta
            |--Marchantiophyta
            |--Bryophyta
            |--Anthocerotophyta
            `--Tracheophyta
                 |--Lycopodiopsida
                 `--o--o--Equisetopsida
                    |  `--Pteridopsida
                    `--Spermatophytata

Introduction

The spermatophytes (also known as phanerogams) comprise those plants that produce seeds. They are a subset of the embryophytes or land plants. The living spermatophytes form five groups:

• cycads, a subtropical and tropical group of plants with a large crown of compound leaves and a stout trunk,
• Ginkgo, a single species of tree,
• conifers, cone-bearing trees and shrubs,
• gnetae, woody plants in the genera Gnetum, Welwitschia, and Ephedra, and
• angiosperms, the flowering plants, a large group including many familiar plants in a wide variety of habitats.

Relationships and nomenclature

Seed-bearing plants were traditionally divided into angiosperms, or flowering plants, and gymnosperms, which includes the gnetae, cycads, ginkgo, and conifers. Angiosperms are now thought to have evolved from a gymnosperm ancestor, which would make gymnosperms a paraphyletic group if it includes extinct taxa. Although not a monophyletic taxonomic unit, "gymnosperm" is still widely used to distinguish the four living taxa of non-flowering, seed-bearing plants from the angiosperms. Molecular phylogenies have conflicted with morphologically-based evidence as to whether extant gymnosperms comprise a monophyletic group. Some morphological data suggests that the Gnetophytes are the sister-group to angiosperms, but molecular phylogenies have generally shown a gymnosperm clade that includes the Gnetophytes as sister-group to the conifers. Cantino et al. (2007) proposed the name Acrogymnospermae for the clade of modern "gymnosperms" if recognised to distinguish it from the traditional usage of the name Gymnospermae.

A traditional classification grouped put all the seed plants in a single division, with classes for our five groups:

• Division Spermatophyta
  • Cycadopsida, the cycads
  • Ginkgoopsida, the ginkgo
  • Pinopsida, the conifers, ("Coniferopsida")
  • Gnetopsida, the gnetae
  • Magnoliopsida, the flowering plants, or Angiospermopsida

In addition to the taxa listed above, the fossil record contains evidence of many extinct taxa of seed plants. The so-called "seed ferns" (Pteridospermae) were one of the earliest successful groups of land plants, and forests dominated by seed ferns were prevalent in the late Paleozoic. Glossopteris was the most prominent tree genus in the ancient southern supercontinent of Gondwana during the Permian period. By the Triassic period, seed ferns had declined in ecological importance, and representatives of modern gymnosperm groups were abundant and dominant through the end of the Cretaceous, when angiosperms radiated.

A more modern classification ranks these groups as separate divisions (sometimes under the Superdivision Spermatophyta):

• Cycadophyta, the cycads
• Ginkgophyta, the ginkgo
• Pinophyta, the conifers
• Gnetophyta, the gnetae
• Magnoliophyta, the flowering plants

Phylogeny

<==Spermatophyta [Acrogymnospermae, Pinophyta, Spermatophytatinae, Spermatophytina, Spermatopsida]
   |  i. s.: Gigantopteris [Gigantonomiales, Gigantopteridaceae]
   |         Sanmiguelia
   |         Irania [Iraniales]
   |         Cycadopites
   |           |--C. carpentieri (Delcourt & Sprumont) Singh 1964
   |           `--C. fragilis Singh 1964
   |         Balmeiopsis limbatus (Balme) Archangelsky 1979
   |         Elaterocolpites castelainii Jardiné & Magloire 1965
   |         Elateroplicites africaensis Herngreen 1973
   |         Elaterosporites
   |           |--E. klaszii (Jardiné & Magloire) Jardiné 1967
   |           `--E. verrucatus
   |         Galeacornea
   |           |--G. causea Stover 1963
   |           `--G. clavis Stover 1963
   |         Steevesipollenites sinuosus Azema & Boltenhagen 1974
   |--Pan-Cycadophyta [Cycadopsida]
   |    |  i. s.: Anomozamites
   |    |         Antarcticycas
   |    |         Michelilloa
   |    |--Lagenostoma [Lagenostomales]
   |    |    `--L. lomaxi
   |    |--Trigonocarpus Brongniart 1828 [Trigonocarpales]
   |    |--Nilssoniaceae [Nilssoniales]
   |    `--+--Semionogyna
   |       `--Cycadophyta
   `--+--Peltaspermales
      |    |--Permotheca
      |    |--Callipteris
      |    |--Comia
      |    |--Tatarina
      |    |--Glossophyllum
      |    |--Pachypteris
      |    `--Peltaspermum
      |--Coniferophyta
      `--+--Pentoxylon
         |--Glossopteris [Arberiales, Glossopteridales]
         `--+--Pan-Angiospermae [Magnoliophyta]
            |    |--Caytonia [incl. Caytonanthus; Caytoniales]
            |    |--Leptostrobus
            |    `--Apo-Angiospermae
            |         |--Angiospermae
            |         `--Archaefructus [Archaefructaceae]
            |              |--*A. liaoningensis
            |              `--A. sinensis Sun, Ji et al. 2002
            `--Pan-Gnetophyta
                 |--+--Gnetales
                 |  `--Piroconites
                 |--Erdtmanithecales
                 |    |--Erdtmanispermum balticum
                 |    |--Eucommiidites
                 |    |    |--E. minor Groot & Penny 1960
                 |    |    `--E. troedsonii Erdtmann 1948
                 |    |--Spermatites
                 |    |    |--S. pattensis
                 |    |    `--S. patuxensis
                 |    |--Erdtmanitheca texensis
                 |    |--Eucommiitheca hirsuta
                 |    `--Bayeritheca hughesii
                 `--Bennettitales
                      |--Weltrichia
                      |--Cycadeoidea
                      |    |--C. albiana [=Bennettites albianus]
                      |    |--C. dacotensis
                      |    |--C. dartoni
                      |    |--C. gibsoniana
                      |    |--C. maccafferyi
                      |    `--C. morierei [=Williamsonia morierei, Bennettites morierei]
                      |--Sturiella
                      |--Zamites
                      |--Vardekloeftia sulcata [incl. V. conica]
                      |--Cycadeoidella japonica
                      |--Williamsonia
                      |    |--W. bockii
                      |    |--W. himas
                      |    |--W. scotica
                      |    `--W. sewardiana
                      `--Bennettites crossospermus

* Type species of generic name indicated

References

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Bowe, L. M., G. Coat & C. W. dePamphilis. 2000. Phylogeny of seed plants based on all three genomic compartments: extant gymnosperms are monophyletic and Gnetales' closest relatives are conifers. Proceedings of the National Academy of Sciences 97: 4092-4097.

Cantino, P. D., J. A. Doyle, S. W. Graham, W. S. Judd, R. G. Olmstead, D. E. Soltis, P. S. Soltis & M. J. Donoghue. 2007. Towards a phylogenetic nomenclature of Tracheophyta. Taxon 56 (3): E1-E44.

Chaw, S.-M., C. L. Parkinson, Y. Cheng, T. M. Vincent & J. D. Palmer. 2000. Seed plant phylogeny inferred from all three plant genomes: monophyly of extant gymnosperms and origin of Gnetales from conifers. Proceedings of the National Academy of Sciences 97: 4086-4091 (abstract here).

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Friedman, W. E., & S. K. Floyd. 2001. Perspective: The origin of flowering plants and their reproductive biology – a tale of two phylogenies. Evolution 55 (2): 217-231.

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