Athrotaxis
Athrotaxis Temporal range:
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Athrotaxis cupressoides | |
Scientific classification | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Gymnospermae |
Division: | Pinophyta |
Class: | Pinopsida |
Order: | Cupressales
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Family: | Cupressaceae |
Subfamily: | Athrotaxidoideae Quinn |
Genus: | Athrotaxis D.Don[1] |
Type species | |
Athrotaxis selaginoides Don
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Species | |
See text |
Athrotaxis is a genus of two to three species (depending on taxonomic opinion) of
They are medium-sized evergreen trees, reaching 10–30 m (rarely 40 m) tall and 1-1.5 m trunk diameter. The leaves are scale-like, 3–14 mm long, are borne spirally on the shoots. The cones are globose to oval, 1–3 cm diameter, with 15-35 scales, each scale with 3-6 seeds; they are mature in 7–9 months after pollination, when they open to release the seeds. The male (pollen) cones are small, and shed their pollen in early spring.[2]
They are very susceptible to
Classification
Taxonomy
Athrotaxis is the only living genus of the subfamily Athrotaxidoideae. A 2021 molecular study found the Athrotaxidoideae to be the sister group to the Sequoioideae, which contains famously massive species such as the coast redwood (Sequoia sempervirens) and giant sequoia (Sequoiadendron giganteum). This is despite both subfamilies' current distributions being on entirely different hemispheres. The study indicates that both taxa diverged during the mid to late Jurassic.[3] The oldest fossil of the genus is known from the Early Cretaceous (Aptian) of Santa Cruz Province in Argentina, South America, with other fossils of the genus known from New Zealand, eastern Australia, and possibly North America. Other fossils of the subfamily are known from the Late Jurassic of Europe, as well as the Early Cretaceous of North America and China,[4] as well as possibly the Early Cretaceous of Europe, and Late Cretaceous of South America and North America.[5]
Species
Phylogeny of Athrotaxis[6][7] | |||||||||||||||
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The three taxa of Athrotaxis are variously treated as three distinct species, or as two species, with the third taxon being a hybrid between the other two. To date, the evidence has been inconclusive, with some data suggesting hybrid origin, but other evidence suggesting the third is distinct and not a hybrid.[2]
Image | Leaves | Scientific name | Description | Distribution |
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Pencil Pine D.Don . |
Leaves short, 3–5 mm, adpressed tightly on the shoots. Cones small, 1-1.5 cm, scales with a small bract only covering the centre of the scale. | Tasmania, Australia. | ||
King Billy Pine or King William Pine Athrotaxis selaginoides D.Don. |
Leaves long, 8–14 mm, spreading out from the shoots. Cones large, 2–3 cm, scales with a large bract nearly completely covering the scale. | Tasmania, Australia. | ||
Athrotaxis laxifolia Hook. | (? A. cupressoides × A. selaginoides). Leaves short, 4–7 mm, spreading out from the shoots. Cones intermediate, 1.5-2.5 cm, scales with a medium bract covering most of the scale. | Tasmania, Australia. |
Cultivation and uses
The
Examples of the species and many of its leaf forms may be seen in the living collections at
References
- ^ "Athrotaxis". Australian Plant Name Index (APNI). Centre for Plant Biodiversity Research, Australian Government. Retrieved 16 March 2023.
- ^ ISBN 1-84246-068-4
- S2CID 236141481.
- .
- ISSN 1674-4918.
- S2CID 232282918.
- )