Podocarpaceae

Taxobox
name = Podocarpaceae


image_width = 240px
image_caption = "Podocarpus macrophyllus" foliage and mature seed cones
regnum = Plantae
divisio = Pinophyta
classis = Pinopsida
ordo = Pinales
familia = Podocarpaceae
familia_authority = Endl.
subdivision_ranks = Genera
subdivision = "Acmopyle"
"Afrocarpus"
"Dacrycarpus"
"Dacrydium"
"Falcatifolium"
"Halocarpus"
"Lagarostrobos"
"Lepidothamnus"
"Manoao"
"Microcachrys"
"Microstrobos"
"Nageia"
"Parasitaxus"
"Phyllocladus"
"Podocarpus"
"Prumnopitys"
"Retrophyllum"
"Saxegothaea"
"Sundacarpus"

Podocarpaceae is a large family of mainly Southern Hemisphere conifers, with 18-19 genera and about 170-200 species of evergreen trees and shrubs. 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 Indo-China 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 conifer. It occurs on New Caledonia, where it is parasitic on another member of the Podocarpaceae, "Falcatifolium taxoides".

The genus "Phyllocladus", here included in Podocarpaceae on genetic evidence, is treated by some botanists in its own family "Phyllocladaceae".

Taxonomy

The Podocarpaceae family shows great diversity, both morphologically and ecologically. Its members occur mainly in the southern hemisphere, with most generic 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" L’Hér. ex Pers. (with 107 species) and "Dacrydium" Sol. ex Forst. are the largest genera. A few genera are common to New Zealand and South America, supporting the view that the 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 recognised - "Podocarpus", "Dacrydium", "Phyllocladus", "Acmopyle", "Microcachrys", "Saxegothaea" and "Pherosphaera". All the African taxa fell under "Podocarpus" - "P. falcatus", "P. elongatus", "P. henkelii" and "P. latifolius". Taxonomists divided "Podocarpus" species into eight categories 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 & 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). [http://eprints.ru.ac.za/126/01/sajsci_v100_n11_a26%5B1%5D.pdf 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.]

References

*Quinn, C. J. & Price, R. A. Phylogeny of the Southern Hemisphere Conifers. "Proc. Fourth International Conifer Conference" 129-136 (2003).

External links

* [http://www.conifers.org/po/index.htm Gymnosperm Database - Podocarpaceae]