Podocarpaceae (Dacrydium Beccarii) (15742645126)

Podocarpaceae is a large family of mainly Southern Hemisphere conifers, known in English as podocarps, comprising about 156 species of evergreen trees and shrubs.James E. Eckenwalder. 2009. ''Conifers of the World''. Portland, Oregon: Timber Press. . It contains 19 genera if '' Phyllocladus'' is included and '' Manoao'' and ''Sundacarpus'' are recognized.

The family is a classic member of the Antarctic flora, with its main centres of diversity in Australasia, particularly New Caledonia, Tasmania, and New Zealand, and to a slightly lesser extent Malesia and South America (primarily in the Andes Mountains). Several genera extend north of the equator into Indochina and the Philippines. '' Podocarpus'' reaches as far north as southern Japan and southern China in Asia, and Mexico in the Americas, and ''Nageia'' into southern China and southern India. Two genera also occur in sub-Saharan Africa, the widespread ''Podocarpus'' and the endemic ''Afrocarpus''.

'' Parasitaxus usta'' is unique as the only known parasitic gymnosperm. It occurs on New Caledonia, where it is parasitic on another member of the Podocarpaceae, '' Falcatifolium taxoides''.William T. Sinclair, R. R. Mill, M. F. Gardner, P. Woltz, T. Jaffré, J. Preston, M. L. Hollingsworth, A. Ponge, and M. Möller. 2002. "Evolutionary relationships of the New Caledonian heterotrophic conifer, ''Parasitaxis usta'' (Podocarpaceae), inferred from chloroplast trnL-F intron/spacer and nuclear rDNA ITS2 sequences". ''Plant Systematics and Evolution'' 233 (1–2): 79–104.

The genus ''Phyllocladus'' is sister to the Podocarpaceae ''sensu stricto''. It is treated by some botanists in its own family, the Phyllocladaceae. Christopher N. Page. 1990. "Phyllocladaceae" pages 317–319. In: Klaus Kubitzki (general editor); Karl U. Kramer and Peter S. Green (volume editors) ''The Families and Genera of Vascular Plants'' volume I. Berlin, Heidelberg: Springer-Verlag.

Taxonomy

The Podocarpaceae show great diversity, both morphologically and ecologically. Members occur mainly in the Southern Hemisphere, with most genetic variety taking place in New Caledonia, New Zealand, and Tasmania. Species diversity of ''Podocarpus'' is found mainly in South America and the Indonesian islands, the latter also being rich in '' Dacrydium'' and '' Dacrycarpus'' species.

''Podocarpus'' (with 82 to 100 species)Christopher N. Page. 1990. "Podocarpaceae" pages 332–346. In: Klaus Kubitzki (general editor); Karl U. Kramer and Peter S. Green (volume editors) ''The Families and Genera of Vascular Plants'' volume I. Berlin, Heidelberg: Springer-Verlag. and ''Dacrydium'' (with 21 species) are the largest genera. A few genera are common to New Zealand and South America, supporting the view that podocarps had an extensive distribution over southern Gondwanaland. The breaking up of Gondwanaland led to large-scale speciation of the Podocarpaceae.

Until 1970, only seven Podocarpaceae genera were recognized: ''Podocarpus'', ''Dacrydium'', ''Phyllocladus'', ''Acmopyle'', ''Microcachrys'', ''Saxegothaea'', and ''Pherosphaera''. All four of the African species fell under ''Podocarpus'' – ''P. falcatus'', ''P. elongatus'', ''P. henkelii'', and ''P. latifolius''. Taxonomists divided ''Podocarpus'' species into eight species groups based on leaf anatomy: ''Afrocarpus'' J.Buchholz & N.E.Gray, ''Dacrycarpus'' Endl., ''Eupodocarpus'' Endl., ''Microcarpus'' Pilg., ''Nageia'' (Gaertn.) Endl., ''Polypodiopsis'' C.E.Bertrand (non ''Polypodiopsis'' Carriére nom. rej. prop. 6), ''Stachycarpus'' Endl. and ''Sundacarpus'' J.Buchholz and N.E.Gray.

Studies of embryology, gametophyte development, female cone structure, and cytology led to the belief that the eight categories probably deserved generic status. Researchers agreed on the need to recognize "fairly natural groupings which prove to have good geographic and probably evolutionary cohesion" and took the necessary steps to raise each section to generic status.Barker, N. P.; Muller, E. M.; and Mill, R. R. (2004)
"A yellowwood by any other name: molecular systematics and the taxonomy of ''Podocarpus'' and the Podocarpaceae in southern Africa"
. ''South African Journal of Science'', 100: 629–632.

In 1990, a treatment of the Podocarpaceae recognized 17 genera, excluding '' Phyllocladus'' from the family, while recognizing ''Sundacarpus'', but not ''Manoao''. In 1995, ''Manoao'' was segregated from '' Lagarostrobus'', based on morphological characteristics. Brian P. J. Molloy. 1995. "''Manoao'' (Podocarpaceae), a new monotypic conifer genus endemic to New Zealand". ''New Zealand Journal of Botany'' 33 (2): 183–201. In 2002, a molecular phylogenetic study showed ''Sundacarpus'' is embedded in ''Prumnopitys'' and the monophyly of ''Lagarostrobos'' is doubtful if ''Manoao'' is included within it. More recent treatments of the family have recognized ''Manoao'', but not ''Sundacarpus''.Aljos Farjon. 2008. ''A Natural History of Conifers''. Portland, Oregon: Timber Press.

Evolution

Molecular evidence supports Podocarpaceae being the sister group to the Araucariaceae, and having diverged from it during the late Permian. While some fossils attributed to the family have been reported from the Late Permian and Triassic, like '' Rissikia'', these cannot be unambiguously assigned to the family. The oldest unambiguous members of the family are known from the Jurassic period, found across both hemispheres, such as '' Scarburgia'' and '' Harrisiocarpus'' from the Middle Jurassic of England, as well as unnamed species from the Middle-Late Jurassic of Patagonia. Modern genera of the family first appeared during the Early Cretaceous, with the family probably reaching an apex of diversity during the early Cenozoic.

''Genera''

Studies based on anatomical, biogeographical, morphological, and DNA evidence suggest these relationships:

List of genera

References

Further reading

* Christopher J. Quinn and Robert A. Price. 2003. "Phylogeny of the Southern Hemisphere Conifers". ''Proceedings of the Fourth International Conifer Conference'': 129–136. doi:10.17660/ActaHortic.2003.615.10

External links

Podocarpaceae
A
The Gymnosperm Database

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Pinales families
Araucariales