| Amborella | ||||||||||||
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 Amborella buds
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| Amborella trichopoda Baill. |
Amborella trichopoda is a rare, vesselless, understory shrub or small tree found only on the island of New Caledonia. It is of great interest in flora taxonomy because modern molecular phylogenetics data place it at or near the base of the flowering plants. That is, it represents a line of flowering plants that very early on diverged (about 130 million years ago) from all the other extant species of flowering plants. Comparing characteristics of this extant basal angiosperm, more derived flowering plants, and the fossil flowering plants may provide clues about the characteristics of early flowering plants and how they have evolved, or changed through time.
Amborella trichopoda is a sprawling shrub or small tree with two-ranked leaves without stipules. The leaves are alternately arranged, evergreen, simple, with serrated and rippled margins, and about 8–10 cm long. The plant is dioecious: each flower produces both stamens and carpels, but only one sex develops fully and is fertile in the flowers of an individual plant, the structures of the other sex remaining undeveloped. The small flowers, 4–8 mm across, are in terminal cymose inflorescences or clusters, each flower with a perianth of undifferentiated tepals arranged in a spiral, rather than in the whorls of more derived flowers. The fruit is a red berry containing a single seed, 5–8 mm long.
It is placed alone in family Amborellaceae. In the APG II system this was left unplaced at order rank, at the base of the angiosperm cladogram. The Angiosperm Phylogeny Website agrees with this phylogeny, but erects the monotypic order Amborellales to contain it.
Individuals of this species in the wild are being reduced by habitat destruction due to overgrazing, fire, mining (one of the most pervasive causes of ecosystem loss in New Caledonia), and urban expansion.
External links
- Amborellaceae in L. Watson and M.J. Dallwitz (1992 onwards). The families of flowering plants: descriptions, illustrations, identification, information retrieval. via Description language for taxonomy
- Ancient plant provides clues to evolutionary mystery (National Science Foundation)
- Description language for taxonomy
- National Tropical Botanical Garden (Hawaii, USA), article with detailed photos of plants in cultivation
- Nova "First Flower" (transcript)
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