''Allocasuarina crassa'', commonly known as Cape Pillar sheoak, is a species of flowering plant in the family

Casuarinaceae The Casuarinaceae are a family of dicotyledonous flowering plants placed in the order Fagales, consisting of four genera and 91 species of trees and shrubs native to eastern Africa, Australia, Southeast Asia, Malesia, Papuasia, and the Pacifi ...

and is endemic to a small area in far south-eastern Tasmania. It is a low shrub to small tree that is

monoecious Monoecy (; adj. monoecious ) is a sexual system in seed plants where separate male and female cones or flowers are present on the same plant. It is a monomorphic sexual system alongside gynomonoecy, andromonoecy and trimonoecy. Monoecy is conne ...

dioecious Dioecy (; ; adj. dioecious , ) is a characteristic of a species, meaning that it has distinct individual organisms (unisexual) that produce male or female gametes, either directly (in animals) or indirectly (in seed plants). Dioecious reproductio ...

, with spreading to erect branchlets up to long, the leaves reduced to scales in whorls of seven to ten, the fruiting cones long containing winged seeds (samaras) long.

Description

''Allocasuarina crassa'' is a dioecious or monoecious shrub that typically grows to a height of , or sometimes a small tree to , and has smooth bark. Its branchlets are spreading to more or less erect, up to long, the leaves reduced to erect, scale-like teeth long, arranged in whorls of seven to ten around the branchlets. The sections of branchlet between the leaf whorls (the "articles") are long and wide and the furrows along the branchlets are hairy. Male flowers are arranged in spikes about long, the

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 ...

long. Female cones are cylindrical and

sessile Sessility, or sessile, may refer to: * Sessility (motility), organisms which are not able to move about * Sessility (botany), flowers or leaves that grow directly from the stem or peduncle of a plant * Sessility (medicine), tumors and polyps that ...

or on a peduncle up to long. Mature cones are long and in diameter, the samaras black long.

Taxonomy

''Allocasuarina crassa'' was first formally described in 1989 by

Lawrie Johnson Lawrence Alexander Sidney Johnson Fellow of the Australian Academy of Science, FAA, (26 June 1925 – 1 August 1997) known as Lawrie Johnson, was an Australian Taxonomy (biology), taxonomic botany, botanist. He worked at the Royal Botanic Garden ...

in the ''

Flora of Australia The flora of Australia comprises a vast assemblage of plant species estimated to over 30,000 vascular and 14,000 non-vascular plants, 250,000 species of fungi and over 3,000 lichens. The flora has strong affinities with the flora of Gondwana, ...

'' from specimens collected b
Tony Moscal
at

Cape Pillar Cape Pillar is a rural locality in the local government area (LGA) of Tasman in the South-east LGA region of Tasmania. The locality is about south-east of the town of Nubeena. The 2016 census recorded a population of 4 for the state suburb of ...

in 1976. The specific epithet, (''crassa'') means "thick" or "stout", referring to the thickness of the articles, compared to those of the related '' A. monolifera'' and '' A. zephyrea''.

Distribution and habitat

Endemic to Tasmania, ''A. crassa'' is restricted to the Cape Pillar area of the

Tasman Peninsula The Tasman Peninsula, officially Turrakana / Tasman Peninsula, is a peninsula located in south-east Tasmania, Australia, approximately by the Arthur Highway, south-east of Hobart. The Tasman Peninsula lies south and west of Forestier Peninsula ...

and

Tasman Island The Tasman Island, part of the Tasman Island Group, is an oval island with an area of , lying close to the south-eastern coast of Tasmania, Australia. The island is located in the Tasman Sea, situated off the Tasman Peninsula and is contained ...

, both of which are in the

Tasman National Park The Tasman National Park is a national park in eastern Tasmania, Australia, approximately east of Hobart. The park is situated on part of both the Forestier and Tasman peninsulas and encompasses all of Tasman Island. History Whaling acti ...

where there are about 100,000 mature individuals. It has a linear extent of distribution of with an area of about . It grows on

dolerite Diabase (), also called dolerite () or microgabbro, is a mafic, holocrystalline, subvolcanic rock equivalent to volcanic basalt or plutonic gabbro. Diabase dikes and sills are typically shallow intrusive bodies and often exhibit fine-grained ...

soils in both wet

eucalypt Eucalypt is a descriptive name for woody plants with capsule fruiting bodies belonging to seven closely related genera (of the tribe Eucalypteae) found across Australasia: ''Eucalyptus'', '' Corymbia'', '' Angophora'', ''Stockwellia'', ''Allosyn ...

forest and in coastal heath and shrubland. On the Cape Pillar plateau it may occur in pure, even-age stands after a long fire-free period.

Conservation status

''Allocasuarina crassa'' is listed as ''rare'' under the Tasmanian TSP Act. The main threat is inappropriate fire regimes. It is also sensitive to the introduced soil-borne pathogen ''

Phytophthora cinnamomi ''Phytophthora cinnamomi'' is a soil-borne water mould that produces an infection which causes a condition in plants variously called "root rot", "dieback", or (in certain '' Castanea'' species), "ink disease". The plant pathogen is one of the wo ...

''.

Gallery

References

{{Taxonbar, from=Q4732987 crassa Fagales of Australia Flora of Tasmania Trees of Australia Plants described in 1989 Tasman National Park Taxa named by Lawrence Alexander Sidney Johnson