Phyllocladus
From Academic Kids
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Five; see text |
Phyllocladus is a small genus of conifers, now treated in the Family Podocarpaceae. They are morphologically very distinct from the other genera in that family, and some botanists treat them in a family of their own, the Phyllocladaceae. However, genetic analysis shows that they fall within the Podocarpaceae; their removal from this family leaves the remainder of Podocarpaceae as a polyphyletic taxon. As modern scientific classification requires taxa to be monophyletic, Phyllocladus is best treated within the Podocarpaceae.
This genus is mainly a southern hemisphere genus, occurring in New Zealand, Tasmania and Malesia, where one species crosses a short way north of the equator in the Philippines.
They are small to medium-size trees, reaching 10-30 m tall. The main structural shoots are green for 2-3 years, then turn brown as the bark thickens. The leaves are sparse, tiny, scale-like, 2-3 mm long, and only green (photosynthetic) for a short time, soon turning brown. Most photosynthesis is performed by highly modified, leaf-like short shoots called phylloclades; these develop in the axils of the scale leaves, and are simple or compound (depending on species). Simple phylloclades are rhombic, 2-5 cm long, and compound phylloclades are up to 20 cm long and subdivided into 5-15 'leaflet'-like phylloclades 1-3 cm long. The seed cones are berry-like, similar to those of several other Podocarpaceae genera, notably Halocarpus and Prumnopitys, with a fleshy white aril; the seeds are dispersed by birds, which digest the soft fleshy aril as they pass the hard seeds in their droppings.
- Species
- Phyllocladus alpinus (P. trichomanoides var. alpinus) - Mountain Toatoa (New Zealand)
- Phyllocladus asplenifolius - Celery-top-pine (Tasmania)
- Phyllocladus hypophyllus - Malesian Celery-pine (New Guinea to Borneo & Philippines)
- Phyllocladus toatoa - Toatoa (New Zealand)
- Phyllocladus trichomanoides - Tanekaha (New Zealand)
Reference
Quinn, C. J. & Price, R. A. 2003. Phylogeny of the Southern Hemisphere Conifers. Proc. Fourth International Conifer Conference: 129-136.
External link
Gymnosperm Database - Phyllocladus (http://www.botanik.uni-bonn.de/conifers/po/ph/index.htm)nl:Phyllocladus
