Callitris is a genus of coniferous trees in the Cupressaceae (cypress family). There are 15 species in the genus, of which 13 are native to Australia and the other two (C. neocaledonica, C. sulcata) native to New Caledonia. Traditionally the most widely used common name is cypress-pine, a name shared by the closely related genus Actinostrobus. However, this is inaccurate as these are cypress and in no way pines, and they are increasingly being called cypress.
They are small to medium-sized trees or large shrubs, reaching 5–25 m tall (to 40 m in C. macleayana). The leaves are evergreen and scale-like, except young seedlings, where they are needle-like; in C. macleayana, needle-like leaves are found mixed with scale leaves throughout the tree’s life. The scales are arranged in six rows along the twigs, in alternating whorls of three (often in whorls of four in C. macleayana).
The male cones are small, 3–6 mm long, and are located at the tips of the twigs. The female cones start out similarly inconspicuous, maturing in 18–20 months to 1–3 cm long and wide, globular to ovoid (acute in C. macleayana), with six overlapping, thick, woody scales, arranged in two whorls of three (often 8 scales in C. macleayana). The cones remain closed on the trees for many years, opening only after being scorched by a bushfire; this then releases the seeds to grow on the newly cleared burnt ground.
The genus is divided into two sections, with the atypical C. macleayana in sect. Octoclinis, and all the other species in sect. Callitris. Some botanists treat C. macleayana in a separate genus, as Octoclinis macleayana. C. macleayana is also distinct in occurring in rainforest on the east coast of Australia; the other species all grow on dry sites.
The closest relatives of Callitris are Actinostrobus from southwest Western Australia, which differs in its cones having several basal whorls of small sterile scales, and Neocallitropsis from New Caledonia, distinct in its needle-like leaves throughout the life of the plant (not just seedlings) and always arranged in whorls of four (not three).
The wood of cypress-pines is light, soft and aromatic. It can be easily split and resists decay, cypress-pine also is termite resistant. It is used to make furniture, indoor and outdoor panelling, and fence posts. Cypress-pines are occasionally planted as ornamental trees, but their use is restricted by the high risks imposed by their very high flammability in bushfires.
Callitris columellaris is naturalised in southern Florida, where it is usually known by the synonym Callitris glaucophylla.
In 2010, early Oligocene fossilized foliage and cones of Callistris were unearthed near the Lea River in Tasmania. The fossils were given the name Callitris leaensis and represent the oldest known representative of the genus.Attributed from: Wikipedia