Actinostrobus
Encyclopedia
Actinostrobus is a genus of coniferous tree
s in the Cupressaceae
(cypress family). Common names include cypress, sandplain-cypress and cypress-pine, the last of these shared by the closely related genus Callitris
. There are three species in the genus, all endemic
to southwestern Western Australia
:
They are shrub
s or small tree
s, reaching 3 – tall. The leaves
are evergreen
, of two forms; juvenile needle-like leaves 10 – long on young seedlings (but occasional into adulthood in A. acuminatus), and scale-like adult leaves, 2 – 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, 3 – long, and are located at the tips of the twigs. The female cones start out similarly inconspicuous, maturing in eighteen to twenty months to 10 – 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
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
, 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.
Tree
A tree is a perennial woody plant. It is most often defined as a woody plant that has many secondary branches supported clear of the ground on a single main stem or trunk with clear apical dominance. A minimum height specification at maturity is cited by some authors, varying from 3 m to...
s in the Cupressaceae
Cupressaceae
The Cupressaceae or cypress family is a conifer family with worldwide distribution. The family includes 27 to 30 genera , which include the junipers and redwoods, with about 130-140 species in total. They are monoecious, subdioecious or dioecious trees and shrubs from 1-116 m tall...
(cypress family). Common names include cypress, sandplain-cypress and cypress-pine, the last of these shared by the closely related genus Callitris
Callitris
Callitris is a genus of coniferous trees in the Cupressaceae . There are 15 species in the genus, of which 13 are native to Australia and the other two native to New Caledonia. Traditionally the most widely used common name is cypress-pine, a name shared by the closely related genus Actinostrobus...
. There are three species in the genus, all endemic
Endemic (ecology)
Endemism is the ecological state of being unique to a defined geographic location, such as an island, nation or other defined zone, or habitat type; organisms that are indigenous to a place are not endemic to it if they are also found elsewhere. For example, all species of lemur are endemic to the...
to southwestern Western Australia
Western Australia
Western Australia is a state of Australia, occupying the entire western third of the Australian continent. It is bounded by the Indian Ocean to the north and west, the Great Australian Bight and Indian Ocean to the south, the Northern Territory to the north-east and South Australia to the south-east...
:
- Actinostrobus acuminatusActinostrobus acuminatusActinostrobus acuminatus is a species of coniferous tree in the Cupressaceae . Like the other species in the genus, it is endemic to southwestern Western Australia, where it can be found along the shorelines of rivers...
- Dwarf cypress, Creeping pine, Moore cypress pine - Actinostrobus arenariusActinostrobus arenariusActinostrobus arenarius is a species of conifer in the Cupressaceae family, also known as Sandplain-cypress or Sandplain cypress.It is found only in Western Australia.-References:...
- Sandplain-cypress - Actinostrobus pyramidalisActinostrobus pyramidalisActinostrobus pyramidalis, commonly known as swamp cypress, is a species of coniferous tree in the Cupressaceae . Like the other species in the genus, it is endemic to southwestern Western Australia....
- Swan river cypress, Swamp cypress, Western Australian swamp cypress, King George's cypress pine
They are shrub
Shrub
A shrub or bush is distinguished from a tree by its multiple stems and shorter height, usually under 5–6 m tall. A large number of plants may become either shrubs or trees, depending on the growing conditions they experience...
s or small tree
Tree
A tree is a perennial woody plant. It is most often defined as a woody plant that has many secondary branches supported clear of the ground on a single main stem or trunk with clear apical dominance. A minimum height specification at maturity is cited by some authors, varying from 3 m to...
s, reaching 3 – tall. The leaves
Leaf
A leaf is an organ of a vascular plant, as defined in botanical terms, and in particular in plant morphology. Foliage is a mass noun that refers to leaves as a feature of plants....
are evergreen
Evergreen
In botany, an evergreen plant is a plant that has leaves in all seasons. This contrasts with deciduous plants, which completely lose their foliage during the winter or dry season.There are many different kinds of evergreen plants, both trees and shrubs...
, of two forms; juvenile needle-like leaves 10 – long on young seedlings (but occasional into adulthood in A. acuminatus), and scale-like adult leaves, 2 – long with only the apex free. The leaves are arranged in six rows along the twigs, in alternating whorls of three.
The male cones
Conifer cone
A cone is an organ on plants in the division Pinophyta that contains the reproductive structures. The familiar woody cone is the female cone, which produces seeds. The male cones, which produce pollen, are usually herbaceous and much less conspicuous even at full maturity...
are small, 3 – long, and are located at the tips of the twigs. The female cones start out similarly inconspicuous, maturing in eighteen to twenty months to 10 – 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
Seed
A seed is a small embryonic plant enclosed in a covering called the seed coat, usually with some stored food. It is the product of the ripened ovule of gymnosperm and angiosperm plants which occurs after fertilization and some growth within the mother plant...
s to grow on the newly cleared burnt ground.
The closest relative of Actinostrobus is Callitris
Callitris
Callitris is a genus of coniferous trees in the Cupressaceae . There are 15 species in the genus, of which 13 are native to Australia and the other two native to New Caledonia. Traditionally the most widely used common name is cypress-pine, a name shared by the closely related genus Actinostrobus...
, which is much more widespread, occurring in most of Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
, 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.