Livistona mariae


Livistona mariae, also known as the central Australian or red cabbage palm, is a species of flowering plant in the family Arecaceae.
It is found only in Australia with the best-known occurrence found in Palm Valley in Finke Gorge National Park, Northern Territory. There are more than 3,000 cabbage palms in Palm Valley, many of which are several hundred years old and form a lush oasis among the rugged rocks and gorges. This region is now largely dry Central Ranges xeric scrubland.
The palms are not relics from a previous age when Central Australia was much wetter, as previously thought.
Aboriginal legend recorded in 1894 by Carl Strehlow describes "gods from the north" bringing the seeds to Palm Valley, which concords with the more modern research.

Taxonomy

A species of Livistona, palm trees of the family Arecaceae found in southern Africa, Asia and Australia. The description was published by Ferdinand Mueller in his Fragmenta phytographiae Australiae. Livistona mariae was found by Ernest Giles on his first expedition to the arid interior of Australia. Mueller referred to the taxon in an earier work describing the Giles expedition, although this was published without a formal description.
A lectotype for Mueller's description was nominated in A. N. Rodd's 1998 revision of the genus, identifying one of two specimen sheets at the Melbourne herbarium attributed to Giles, and noted the partial misapplication of the name to Livistona alfredii by Mueller in the same work.
Research that concluded a human agency introduced the plants to the area has resulted in changes to the population's taxonomic treatment and, consequently, required reappraisal of their conservation status as a species naturalised around 15000 years ago rather than an endemic persisting since the Miocene era.
The authors preparing a treatment of Australian populations of the family Arecaceae for the Flora of Australia, published a note that recognised a previously described species Livistona rigida in Rodd's new combination at the rank of subspecies. Another new taxon, describing specimens collected by Rodd in Western Australia and included in his revision of the genus is also recognised. The circumscription of the species may be summarised as,
The common names applied to the species include cabbage palm, central Australian cabbage palm, and red cabbage palm.

Ecology

The occurrence of the isolated population, with its nearest relative – then named as Livistona rigida Becc. – found over one thousand kilometres away, had been supposed to be a relictual species. The isolation of the population was supposed to have resulted from the increased aridity of the continent since the Miocene period, around fifteen million years before the present day, or conveyed by a river or other means of dispersal.
An analysis of molecular evidence found a separation from L. rigida was strongly indicated to have occurred around fifteen thousand years ago.
Revision and exclusion of other potential means for the introduction of the palm to the region, such as fruit bats and other distribution mechanisms, left the parsimonious explanation that it was subject to dispersal by humans. This accords with the myths of local peoples, which allude to its deliberate introduction, the use as a resource and food, and its conservation.

Description

A palm tree with shallow roots and large hairless fronds that are slightly waxy at the underside.
The height of the plant may be over twenty metres, with leaves over four metres on long petioles of a similar length. The base of the tree becomes wider and raised at an advanced age, the trunk gently tapers to a narrower width toward the crown.
Description of the larger groves of this tree, which had been bypassed by the Giles expedition, was provided by a minister at Hermannsburg community.

Distribution and habitat

The distribution range of the species is restricted to a locality known as the Palm Valley Oasis, an area where the Finke River passes through the MacDonnell Ranges. A subsurface aquifer has provided constant moisture to the groves, in an area surrounded by extremes of climate, and the trees occupy niches within the landscape that insulate them from periodic flooding.

Cultivation

The species is represented in cultivation by two of the subspecies, from the central desert and tropical coast. Livistona mariae are slow growing specimens that eventually attain a large height and the emblematic form of a 'palm tree'.
The subspecies Livistona mariae subsp. mariae is a desirable garden specimen referred to as the central Australian cabbage palm and presented as a feature plant. An example in an exhibition of modern gardens – along with the MacDonnell Ranges Cycad Macrozamia macdonnellii from the same region – sought to demonstrate the horticultural potential of central Australia flora at the Geelong Botanic Gardens.
A potentially tall tree with attractive foliage and fruit, Livistona mariae subsp. mariae has a may attain a height of 15 metres in cultivation. The surface pattern of the trunk is regular and neat in appearance, a feature of the persistent leaf bases of the earlier growth, and the width gradually narrows toward the crown. The leaves are reddish during early growth, forming fronds up to 3 m in length and extended out on a long petiole.
Propagation of the plant is from seed sown at the desired site.
The favourable climatic regions in Australia are the arid central regions, when provided with adequate moisture, and the wet tropical coastal to sub-coastal regions of the north-east of Australia, with most success in gardens north of Coffs Harbour.
The cultivated tree formerly named as Livistona rigida is also recognised in horticulture as Livistona mariae subsp. mariae, similar in form to the central desert subspecies but potentially larger in size. The more robust trunk of the subspecies may reach a height of 20 m and the leaves, also reddish when young, reach lengths up to 4 metres.

Conservation status

The three subspecies are listed in various regional and national conservation plans, the status and trajectory of these populations is classified separately. This recognises an arrangement by A. N. Rodd that placed Livistona rigida and Livistona mariae and a newly recognised taxon in a subspecific arrangement.
The remote population at Finke Gorge, once listed as Livistona mariae, was amended to Livistona mariae subsp. mariae for conservation purposes following its taxonomic revision.
The significance of these palms was recognised in a national conservation plan intended to improve the trajectory of thirty Australian plants, actions that would reduce factors that threaten the trees with extinction.
The classification by national EPBC legislation is vulnerable, with identified threats including an increased risk of fire as a result of invasive grasses, couch and buffel grass, alterations to availability of ground water and the impact of increased tourism.
A large number of the trees are protected by occurring within the Finke Gorge National Park, some fringing groves of the palm are found on pastoral land and tourist areas and are subject to separate conservation actions.