Lord Howean BioProvince
This BioProvince (as defined by Armen Takhtajan) includes the sub-tropical, volcanic islands of Lord Howe and Ball’s Pyramid, situated in the Tasman Sea. The island is the remnant of a now-extinct volcano that developed some seven million years ago. The flora consists of about 226 vascular plants including 5 endemic genera (Hedyscepe, Howea, Lepidorrhachis, Lordhowea and Negria), and about 106 endemic species and sub-species. Colmeiroa (previously represented by C. carpodetoides) was also thought to be a monotypic genus confined to this island but is now considered to be a species of Corokia (Escalloniaceae). This degree of endemism shows that the flora is very ancient but in addition, it is thought to have a relict character since most of the genera are represented by no more than two or three species. Despite being closer to Australia the majority of taxa have affinities with New Zealand's flora. For example, the rare endemic Carmichaelia exsul (Fabaceae) is the only species of this genus found outside New Zealand. However, the flora does have a small Australian element but characteristic Australian genera such as Acacia, Casuarina and Eucalytpus, and the family Proteaceae are absent. There is also a small Polynesian element, and one genus, Dietes (represented by the endemic Dietes robinsoniana) is otherwise endemic to South Africa. Also of considerable interest is the presence of Bubbia howeana (Winteraceae). This primitive genus can also be found in Queensland and on the islands of Madagascar and New Caledonia, and was part of the ancient indigenous flora of Gondwanaland. Of significance is the absence of this genus on more recently developed islands such as Vanuatu (New Hebrides). The climate and soil of Lord Howe Island favours the development of temperate rainforest but in the coastal zones the forest gives way to a variety of maritime formations. These including coastal scrub, tussock sedge and succulent halophytes on coastal cliffs, sand dune and sand flat vegetation in some of the sheltered bays, and mangrove in the inter-tidal zone.
The following accounts for this BioProvince have been written or will be written with particular reference to endemic and locally important species. Accounts available are displayed in green or yellow. Those displayed in red are either in the pipeline or awaiting expert contributions.
|Endemic Vascular Plant Flora|