''Actinostrobus'' is a genus of

conifer Conifers () are a group of conifer cone, cone-bearing Spermatophyte, seed plants, a subset of gymnosperms. Scientifically, they make up the phylum, division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a sin ...

ous

tree In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, e.g., including only woody plants with secondary growth, only ...

s in the

Cupressaceae Cupressaceae or the cypress family is a family of conifers. The family includes 27–30 genera (17 monotypic), which include the junipers and redwoods, with about 130–140 species in total. They are monoecious, subdioecious or (rarely) dioecio ...

(cypress family). Common names include cypress, sandplain-cypress and cypress-pine, the last of these shared by the closely related genus '' Callitris''.

Species

There are three species in the genus, all

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

to southwestern

Western Australia Western Australia (WA) is the westernmost state of Australia. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to the south, the Northern Territory to the north-east, and South Australia to the south-east. Western Aust ...

: A 2010 study of ''Actinostrobus'' and ''Callitris'' has placed all three species of ''Actinostrobus'' within an expanded ''Callitris'' based on analysis of 42 morphological and anatomical characters. They are

shrub A shrub or bush is a small to medium-sized perennial woody plant. Unlike herbaceous plants, shrubs have persistent woody stems above the ground. Shrubs can be either deciduous or evergreen. They are distinguished from trees by their multiple ...

s or small

s, reaching tall. The

leaves A leaf (: leaves) is a principal appendage of the stem of a vascular plant, usually borne laterally above ground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, stem, ...

are

evergreen In botany, an evergreen is a plant which has Leaf, foliage that remains green and functional throughout the year. This contrasts with deciduous plants, which lose their foliage completely during the winter or dry season. Consisting of many diffe ...

, of two forms; juvenile needle-like leaves long on young seedlings (but occasional into adulthood in ''A. acuminatus''), and scale-like adult leaves, long with only the apex free. The leaves are arranged in six rows along the twigs, in alternating whorls of three. The male cones are small, long, and are located at the tips of the twigs. The female cones start out similarly inconspicuous, maturing in eighteen to twenty months to long and wide, globular to acute-ovoid, with six thick, woody scales, arranged in two whorls of three, and a further nine to fifteen thin, sterile basal scales. The cones remain closed on the trees for many years, opening only after being scorched by a bushfire; this then releases the

seed In botany, a seed is a plant structure containing an embryo and stored nutrients in a protective coat called a ''testa''. More generally, the term "seed" means anything that can be Sowing, sown, which may include seed and husk or tuber. Seeds ...

s to grow on the newly cleared burnt ground. The closest relative of ''Actinostrobus'' is '' Callitris'', which is much more widespread, occurring in most of

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

, and differs in its cones lacking the basal whorls of small sterile scales. The wood of ''Actinostrobus'' is light, soft and aromatic, but the plants are too small for any significant use. They are occasionally planted as ornamental shrubs, but their use is restricted by the high risks imposed by their very high flammability in bushfires.

References

* *Farjon, A. (2005). ''Monograph of Cupressaceae and Sciadopitys''. Royal Botanic Gardens, Kew. .
Gymnosperm Database - ''Actinostrobus''
{{Taxonbar, from=Q1472074 Flora of Western Australia Pinales of Australia Conifer genera