''Caustis blakei'', also known as the koala fern, is a species of rhizomatous sedge in the family

Cyperaceae The Cyperaceae are a family of graminoid (grass-like), monocotyledonous flowering plants known as sedges. The family is large, with some 5,500 known species described in about 90 genera, the largest being the "true sedges" genus '' Carex'' ...

. It is found exclusively in Australia in southeastern

Queensland ) , nickname = Sunshine State , image_map = Queensland in Australia.svg , map_caption = Location of Queensland in Australia , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , established_ ...

and northeastern

New South Wales ) , nickname = , image_map = New South Wales in Australia.svg , map_caption = Location of New South Wales in AustraliaCoordinates: , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , es ...

. It has rigid, smooth stems up to 2 meters with 10 to 28 nodes. It has two subspecies: ''C. blakei'' subsp''. blakei'' and ''C. blakei'' subsp''. macrantha'', which was identified by Johnston et al. in 1997. The two subspecies differ in length of

spikelets A spikelet, in botany, describes the typical arrangement of the flowers of grasses, sedges and some other Monocots. Each spikelet has one or more florets. The spikelets are further grouped into panicles or spikes. The part of the spikelet that ...

anthers The stamen (plural ''stamina'' or ''stamens'') is the pollen-producing reproductive organ of a flower. Collectively the stamens form the androecium., p. 10 Morphology and terminology A stamen typically consists of a stalk called the filam ...

, and fruit.

Habitat

''Caustis blakei'' is found in tall

eucalyptus ''Eucalyptus'' () is a genus of over seven hundred species of Flowering plant, flowering trees, shrubs or Mallee (habit), mallees in the Myrtaceae, myrtle Family (biology), family, Myrtaceae. Along with several other genera in the Tribe (biology) ...

forests with sparse or closed canopies in sandy soils or soils derived from weathered

sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates ...

. ''C. blakei subsp. blakei'' occurs in mainland Australia from Toolara in Queensland to

Crowdy Bay National Park Crowdy Bay is a national park in New South Wales, Australia, 271 km northeast of Sydney. It is a great seaside retreat, close to Port Macquarie, offering hiking trails, coastal picnics, fishing, and great opportunities to observe wildli ...

in New South Wales, with additional populations identified on

Fraser Island Fraser Island ( Butchulla: ) is a World Heritage-listed island along the south-eastern coast in the Wide Bay–Burnett region, Queensland, Australia. The island is approximately north of the state capital, Brisbane, and is within the Fra ...

Moreton Island Moreton Island (Mulgumpin) is an island on the eastern side of Moreton Bay on the coast of South East Queensland, Australia. The Coral Sea lies on the east coast of the island. Moreton Island lies northeast of the Queensland capital, Brisbane. ...

, and

Stradbroke Island Stradbroke Island, also known as Minjerribah, was a large sand island that formed much of the eastern side of Moreton Bay near Brisbane, Queensland until the late 19th century. Today the island is split into two islands: North Stradbroke Isl ...

. Geographically isolated, inland populations of ''C. blakei'' subsp''. macrantha'' have been identified in

Murphys Creek Murphys Creek is a rural town and locality in the Lockyer Valley Region, Queensland, Australia. In the , the locality of Murphys Creek had a population of 629 people. Geography The locality is located at the foot of the Great Dividing Range. ...

Esk Esk or ESK may refer to: Places * Esk, Queensland, Australia * Esk Island, in the Great Palm Island group, Queensland, Australia * River Esk (disambiguation), also Esk River * Shire of Esk, a former local government area in Queensland, Australia ...

, and

Helidon Helidon () may refer to: * Helidon, Queensland, town in Lockyer Valley, Queensland, Australia ** Helidon railway station, serving the town of Helidon on the Main line in Queensland, Australia * , a music label in Ljubljana, Slovenia *Helidon Gjergj ...

Description

''Caustis blakei'' is a slow-growing plant that has adapted to acidic, sandy soils that have high levels of iron and low levels of phosphorus. As a result, it is capable of inducing dauciform roots as a morphological response to growing in soil that is deficient of these essential minerals. These roots function similarly to

cluster roots Cluster roots, also known as proteoid roots, are plant roots that form clusters of closely spaced short lateral rootlets. They may form a two- to five-centimetre-thick mat just beneath the leaf litter. They enhance nutrient uptake, possibly by chem ...

in exuding phosphatases and carboxylates to aid in chemically mobilizing scarce soil nutrients.

Threats

Although ''C. blakei subsp. blakei'' is common in coastal areas, including land protected as national parks and World Heritage Sites areas, there is no government protection for the inland areas where ''C. blakei'' subsp''. macrantha'' is found. ''C. blakei'' subsp''. macrantha'' is also under greater pressure from urban development,

bushfires A wildfire, forest fire, bushfire, wildland fire or rural fire is an unplanned, uncontrolled and unpredictable fire in an area of combustible vegetation. Depending on the type of vegetation present, a wildfire may be more specifically identif ...

due to lower rainfall in inland areas that increases fire risk while lowering growth rates, and harvesting for export. Fresh and dried stems of ''Caustis blakei'' are exported from Australia to Europe, Japan, and the US, as well as domestically in Australia. Over one million stems are exported annually. These are harvested from natural populations because commercial propagation of ''Caustis blakei'' is not possible. Because much of the land where populations of ''C. blakei subsp. blakei'' are found is protected, bush-harvesting is most common in the inland populations of ''C. blakei'' subsp''. macrantha''. Efforts to domesticate ''Caustis blakei'' for commercial export have been ongoing since 1996.

References

{{Taxonbar, from=Q15584296 blakei Flora of Australia