Callitris

Callitris is a genus of coniferous 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 in the Cupressaceae

Cupressaceae

The Cupressaceae or cypress family is a conifer family with worldwide distribution. The family includes 27 to 30 genera with about 130-140 species. They are monoecious, subdioecious or dioecious trees and shrubs from 1-116 m tall...

 (cypress family). There are 15 species in the genus, of which 13 are native to Australia

Australia

Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the continental mainland , the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans...

 and the other two (C. neocaledonica, C. sulcata) native to New Caledonia

New Caledonia

New Caledonia , is a "sui generis collectivity" of France located in the region of Melanesia in the southwest Pacific. It comprises a main island , the Loyalty Islands, and several smaller islands...

. Traditionally the most widely used common name is cypress-pine, a name shared by the closely related genus Actinostrobus

Actinostrobus

Actinostrobus is a genus of coniferous trees in the Cupressaceae . Common names include cypress and cypress-pine, the latter name shared by the closely related genus Callitris...

. However, this is inaccurate as these are just cypress and in no way pines, and they are increasingly being called cypress.

They are small to medium-sized 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 or large shrub

Shrub

A shrub or bush is a horticultural rather than strictly botanical category of woody plant, distinguished from a tree by its multiple stems and lower height, usually less than 5-6 m tall. A large number of plants can be either shrubs or trees, depending on the growing conditions they experience...

s, reaching 5-25 m tall (to 40 m in C. macleayana). The leaves

Leaf

In botany, a leaf is an above-ground plant organ specialized for photosynthesis. For this purpose, a leaf is typically flat and thin. There is continued debate about whether the flatness of leaves evolved to expose the chloroplasts to more light or to increase the absorption of carbon dioxide. In...

 are evergreen

Evergreen

In botany, an evergreen plant is a plant having leaves all year round. This contrasts with deciduous plants, which completely lose their foliage for part of the year....

 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

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, 3-6 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

Bushfire

A bushfire is a fire that occurs in the bush . In south east Australia, bushfires tend to be most common and most severe during summer and autumn, in drought years, and particularly severe in El Niño years...

; this then releases the seed

Seed

A seed , referred to as a kernel in some plants, 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 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

Rainforest

Rainforests are forests characterized by high rainfall, with definitions setting minimum normal annual rainfall between 1750–2000 mm . The monsoon trough, alternately known as the intertropical convergence zone, plays a significant role in creating Earth's tropical rain forests.From 40 to 75%...

 on the east coast of Australia; the other species all grow on dry sites.

The closest relatives of Callitris are Actinostrobus

Actinostrobus

Actinostrobus is a genus of coniferous trees in the Cupressaceae . Common names include cypress and cypress-pine, the latter name shared by the closely related genus Callitris...

from southwest Western Australia

Western Australia

Western Australia is a state of Australia, occupying the entire western third of the Australian continent. Australia's largest state and the second largest subnational entity in the world, it has 2.2 million inhabitants , 85% of whom live in the south-west corner of the state.The state's capital...

, which differs in its cones having several basal whorls of small sterile scales, and Neocallitropsis

Neocallitropsis

Neocallitropsis pancheri is a plant species of the family Cupressaceae and the sole species of the genus Neocallitropsis. It is endemic to New Caledonia, where it occurs in small, scattered population along rivers....

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

Florida

Florida is a state located in the southeastern region of the United States, bordering Alabama to the northwest and Georgia to the north. It was the 27th state admitted to the United States...

, where it is usually known by the synonym Callitris glaucophylla.

External links

• Gymnosperm Database - Callitris
• Arboretum de Villardebelle - Photos of cones