Lomatia tasmanica

Lomatia tasmanica, commonly known as King's lomatia, is a shrub of the family Proteaceae native to Tasmania. Growing up to 8 metres (26 ft) tall, the plant has shiny green pinnate (lobed) leaves and bears red flowers in the summer, but yields neither fruit nor seeds. King's lomatia is unusual because all of the remaining plants are genetically identical clones. Because it has three sets of chromosomes (a triploid) and is therefore sterile, reproduction occurs only vegetatively: when a branch falls, that branch grows new roots, establishing a new plant that is genetically identical to its parent.

King's lomatia
Lomatia tasmanica in Hobart Botanical Garden
Scientific classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Order: Proteales
Family: Proteaceae
Genus: Lomatia
Species:
L. tasmanica
Binomial name
Lomatia tasmanica

Charles Denison "Deny" King discovered the plant in 1934, though it was not described until 1967 by botanist Winifred Mary Curtis of the Tasmanian Herbarium. Only one colony of King's lomatia is known to be alive in the wild, consisting of about 600 plants over an area 1.2 km in length.

Description

The individual plants of L. tasmanica are straggly shrubs or small trees to 8 m (26 ft) high, though taller or longer trunked specimens are often bent over. The trunks of very old plants can reach diameters of 8 cm (3.1 in).[3] The upper branchlets are covered in fine rusty fur.[4] The stems may grow roots from nodes on the ground.[5] The leaves are alternately arranged[4] and more crowded towards the ends of branches.[5] Roughly oval in shape, they are 10–18 cm (3.9–7.1 in) long and pinnate, made up of 11 to 25 primary lobes that have irregularly toothed margins and are sometimes subdivided into smaller lobes.[4] The upper surface is green and shiny,[6] while the undersurface is partly hairy, particularly along the midrib. Flowering takes place in February. The terminal flowerheads, or inflorescences, are 9–10 cm (3.5–3.9 in) long.[4]

Taxonomy

Charles Denison "Deny" King "discovered" the plant in May 1934 while mining tin in the remote southwest of Tasmania. Winifred Curtis of the Tasmanian Herbarium named the plant in King's honour in 1967, after he sent specimens he collected at Cox's bight, Port Davey to be identified in 1965. It is also sometimes called "King's holly", though it is not a holly.

L. tasmanica was thought to possibly be a hybrid between L. polymorpha and another species. Genetic analysis using microsatellite markers showed that species found close together geographically are most closely related to each other; L. tasmanica is the sister of a lineage that gave rise to the other two Tasmanian Lomatia species, L. polymorpha and L. tinctoria.[7]

Subfossil remains identical to L. tasmanica were found in 43,600-year-old beds. The climate at that time was most likely as cool as or cooler than it is at Melaleuca today (an average yearly temperature of 11.5 °C, with the coldest month having an average minimum of 4.5 °C and the warmest month an average maximum of 20 °C), and possibly wetter (more than 2400 mm of precipitation annually).[8]

Distribution and habitat

The entire population of Lomatia tasmanica consists of around 300 plants in an area less than 1.2 km long in southwestern Tasmania. The climate is wet, receiving an average total of 1700 mm of rain each year, and all plants grow within 25 metres (82 ft) of a river or creek. L. tasmanica mainly grows in rainforest or mixed forest made up of trees 8–15 metres (26–49 ft) high such as myrtle beech (Lophozonia cunninghamii), celery-top pine (Phyllocladus aspleniifolius), southern sassafras (Atherosperma moschatum), leatherwood (Eucryphia lucida), satinwood (Nematolepis squamea), blue-green tea tree (Leptospermum glaucescens), and horizontal scrub (Anodopetalum biglandulosum), as well as understory species such as thyme archeria (Archeria serpyllifolia), native plum (Cenarrhenes nitida), sweet-scented trochocarpa (Trochocarpa gunnii), Raukaua gunnii, white waratah (Agastachys odorata), climbing heath (Prionotes cerinthoides), hard water fern (Parablechnum wattsii), and brickmaker's sedge (Gahnia grandis). Scattered Smithton peppermint (Eucalyptus nitida) tower over the canopy. Profuse moss and fern growth highlights the wetness of the habitat.

L. tasmanica also extends into neighbouring dry sclerophyll forest composed of Smithton peppermint over an understory of blue-green tea tree on more elevated areas. Finally, it grows in a dense riverbank scrubland with species such as silver banksia (Banksia marginata), mānuka (Leptospermum scoparium), prickly-leaved wattle (Acacia verticillata), swamp honey-myrtle (Melaleuca squamea), scented paperbark (M. squarrosa), horizontal scrub, and Smithton peppermint over a dense low understory of Bauera rubioides, Gahnia grandis, Epacris aff. heteronema, scrambling coral fern (Gleichenia microphylla), Calorophus erostris, lesser wire rush (Empodisma minus), and button grass (Gymnoschoenus sphaerocephalus).[3]

Ecology

Lomatia tasmanica grows in a climate of infrequent bushfires. Fieldwork in the early 2000s established that the area had last been burnt in 1934. Most plants were around 60 years old, though some were estimated at up to 300 years old. The area in which it grows is federally protected, lying wholly within the Southwest National Park.[3]

Although all the plants are technically separate in that each has its own root system, they are collectively considered to be one of the oldest living plant clones. Each plant's lifespan is approximately 300 years, but the plant has been cloning itself for at least 43,600 years and possibly as long as 135,000 years.[9][10] This estimate is based on radiocarbon dating of fossilised leaf fragments that were found 8.5 kilometres (5.3 mi) away from the extant colony. The fossilised fragments are identical to the contemporary plant in cell structure and shape, which suggests that the ancestral and modern plant are also genetically identical. This further implies that the ancestral plant was also triploid and therefore also clonal, due to the extreme rarity of naturally occurring sexually reproducing triploid organisms.

Conservation

Lomatia tasmanica has been declared critically endangered under the Australian government's Environment Protection and Biodiversity Conservation Act 1999.[1] It is also classified at a state level as "Endangered" under the Tasmanian government's Threatened Species Protection Act 1995.[11]

The original plant group that King discovered in 1934 has disappeared (and likely died out), and the sole remaining group of approximately 500 plants covers a 1.2-kilometer-long area in the extreme southwest of Tasmania. This area is prone to fires and other natural threats to the plants, so Tasmania has begun an effort to develop other populations of L. tasmanica in controlled environments such as the Royal Tasmanian Botanical Gardens. Because of its fragility and rarity, their specimens are not on display to the public. Due to its inability to reproduce sexually, there is no possibility of increasing the plant's genetic diversity to promote disease resistance through purely natural means.

However, on 19 September 2009, the Royal Tasmanian Botanical Gardens issued a media release regarding the propagation efforts saying: "The Royal Tasmanian Botanical Gardens [RTBG] is working towards securing the future of a rare and ancient Tasmanian native plant... Lomatia tasmanica, commonly known as King's Lomatia, is critically endangered with less than 500 plants growing in the wild in a tiny pocket of Tasmania's isolated south west. The RTBG has been propagating the plant from cuttings since 1994... 'Fossil leaves of the plant found in the south west were dated at 43,600 years old and given that the species is a clone, it is possibly the oldest living plant in the world".[12]

Infestation with the fungal pathogen Phytophthora cinnamomi has been recorded in other plant species around 20 metres (66 ft) away from some wild L. tasmanica populations. Bushfire could also spread this pathogen and potentially facilitate its infection of the remaining wild plants.[11]

Cultivation

Lomatia tasmanica strikes readily from cuttings but is difficult to keep alive in cultivation,[5] often perishing when dried out. The cuttings are taken in January and February and take up to 12 months to form roots.[13] Like their wild counterparts, the cultivated plants are susceptible to Phytophthora cinnamomi.[3] L. tasmanica has been grafted successfully onto L. tinctoria,[11] and the Botanic Gardens sought to trial grafting it onto L. ferruginea.[13]

See also

References
  1. "Lomatia tasmanica — King's Lomatia". Species Profile and Threats Database. Australian Department of Sustainability, Environment, Water, Population and Communities. Retrieved 11 November 2013.
  2. "Lomatia tasmanica W.M.Curtis". Australian Plant Name Index (APNI), IBIS database. Centre for Plant Biodiversity Research, Australian Government. Retrieved 11 November 2013.
  3. Lynch, A. J. J.; Balmer, J. (2004). "The ecology, phytosociology and stand structure of an ancient endemic plant Lomatia tasmanica (Proteaceae) approaching extinction". Australian Journal of Botany. 52 (5): 619–627. doi:10.1071/BT03023.
  4. "Lomatia tasmanica". Flora of Australia Online. Department of the Environment and Heritage, Australian Government.
  5. Wrigley, John; Fagg, Murray (1991). Banksias, Waratahs and Grevilleas. Sydney, New South Wales: Angus & Robertson. p. 452. ISBN 978-0-207-17277-9.
  6. Threatened Species Unit (1 June 2005). "Lomatia tasmanica" (PDF). Threatened Flora of Tasmania. Retrieved 21 August 2017.
  7. Milner, Melita L.; McIntosh, Emma J.; Crisp, Michael D.; Weston, Peter H.; Rossetto, Maurizio (2013). "Microsatellite variation for phylogenetic, phylogeographic and population-genetic studies in Lomatia (Proteaceae)". Australian Systematic Botany. 26 (3): 186–95. doi:10.1071/SB13002. S2CID 42204696.
  8. Jordan, Greg J.; Carpenter, Raymond J.; Hill, Robert S. (1991). "Late Pleistocene Vegetation and Climate Near Melaleuca Inlet, South-Western Tasmania". Australian Journal of Botany. 39 (4): 315–33. doi:10.1071/BT9910315.
  9. Lynch, A. J. J.; Barnes, R. W.; Vaillancourt, R. E.; Cambecèdes, J. (1998). "Genetic evidence that Lomatia tasmanica (Proteaceae) is an ancient clone" (PDF). Australian Journal of Botany. 46 (1): 25–33. doi:10.1071/BT96120. Retrieved 11 November 2013.
  10. "The Oldest Living Plant Individual". Botanical Electronic News. 8 November 1996. Retrieved 11 November 2013.
  11. Threatened Species Section (2006). "Flora Recovery Plan: King's lomatia, Lomatia tasmanica 2006–2010" (PDF). Hobart, Tasmania: Department of Primary Industries, Water and Environment.
  12. "Botanists collaborate to secure future of rare Tasmanian plant". Royal Tasmanian Botanical Gardens. 11 November 2013. Archived from the original on 14 September 2009.
  13. Tapson, Natalie (2009). "Lomatia tasmanica: A Tasmanian Icon". Hobart, Tasmania: Royal Tasmanian Botanical Gardens. Retrieved 21 August 2017.
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