The Casuarinaceae are a

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

dicot The dicotyledons, also known as dicots (or, more rarely, dicotyls), are one of the two groups into which all the flowering plants (angiosperms) were formerly divided. The name refers to one of the typical characteristics of the group: namely, ...

yledonous

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (). The term angiosperm is derived from the Ancient Greek, Greek words (; 'container, vessel') and (; 'seed'), meaning that the seeds are enclosed with ...

s placed in the order

Fagales The Fagales are an order of flowering plants in the rosid group of dicotyledons, including some of the best-known trees. Well-known members of Fagales include: beeches, chestnuts, oaks, walnut, pecan, hickory, birches, alders, hazels, hornb ...

, consisting of four

genera Genus (; : genera ) is a taxonomic rank above species and below family as used in the biological classification of living and fossil organisms as well as viruses. In binomial nomenclature, the genus name forms the first part of the binomial s ...

and 91 species of trees and shrubs native to eastern

Africa Africa is the world's second-largest and second-most populous continent after Asia. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 20% of Earth's land area and 6% of its total surfac ...

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 ...

Southeast Asia Southeast Asia is the geographical United Nations geoscheme for Asia#South-eastern Asia, southeastern region of Asia, consisting of the regions that are situated south of China, east of the Indian subcontinent, and northwest of the Mainland Au ...

Malesia Malesia is a biogeographical region straddling the Equator and the boundaries of the Indomalayan and Australasian realms. It is a phytogeographical floristic region in the Paleotropical kingdom. It was first recognized as a distinct region ...

Papuasia Papuasia is a Level 2 botanical region defined in the World Geographical Scheme for Recording Plant Distributions (WGSRPD). It lies in the southwestern Pacific Ocean, in the Melanesia ecoregion of Oceania and Tropical Asia. It comprises th ...

, and the

Pacific Islands The Pacific islands are a group of islands in the Pacific Ocean. They are further categorized into three major island groups: Melanesia, Micronesia, and Polynesia. Depending on the context, the term ''Pacific Islands'' may refer to one of several ...

. At one time, all species were placed in the genus ''

Casuarina ''Casuarina'', also known as she-oak, Australian pine and native pine, is a genus of flowering plants in the family Casuarinaceae, and is native to Australia, the Indian subcontinent, Southeast Asia, islands of the western Pacific Ocean, and e ...

''.

Lawrence Alexander Sidney Johnson Lawrence Alexander Sidney Johnson (26 June 1925 – 1 August 1997) known as Lawrie Johnson, was an Australian Taxonomy (biology), taxonomic botany, botanist. He worked at the Royal Botanic Gardens, Sydney, for the whole of his professional car ...

separated out many of those species and renamed them into the new genera of ''

Gymnostoma ''Gymnostoma'' is a genus of about eighteen species of trees and shrubs, constituting one of the four genera of the plant family Casuarinaceae. The species grow naturally in the tropics, including at high elevations having temperate climates, ...

'' in 1980 and 1982, ''

Allocasuarina ''Allocasuarina'', commonly known as sheoak or she-oak, is a genus of flowering plants in the family Casuarinaceae and is endemic to Australia. Plants in the genus ''Allocasuarina'' are trees or shrubs with soft, pendulous, green branchlets, th ...

'' in 1982, and ''

Ceuthostoma ''Ceuthostoma'' is a genus of two species of trees, constituting part of the plant family Casuarinaceae. They grow naturally only in Malesia, in the islands of Palawan, Borneo, Halmahera and New Guinea New Guinea (; Hiri Motu: ''Niu Gini ...

'' in 1988, with some additional formal descriptions of new species in each other genus. At the time, it was somewhat controversial. The

monophyly In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria: # the grouping contains its own most recent comm ...

of these genera was later supported in a 2003 phylogenetic study of the family. In the

Wettstein system A list of systems of plant taxonomy, system of plant taxonomy, the Wettstein system recognised the following main groups, according to Richard Wettstein's ''Handbuch der Systematischen Botanik'' (1901–1924). 3rd edition (1924) Outline Syn ...

, this family was the only one placed in the order Verticillatae. Likewise, in the Engler, Cronquist, and

Kubitzki system The Kubitzki system is a system of plant taxonomy devised by Klaus Kubitzki, and is the product of an ongoing survey of vascular plants, entitled ''The Families and Genera of Vascular Plants'', and extending to 15 volumes in 2018. The survey, in t ...

s, the Casuarinaceae were the only family placed in the order Casuarinales. Members of this family are characterized by drooping equisetoid (meaning "looking like ''

Equisetum ''Equisetum'' (; horsetail) is the only living genus in Equisetaceae, a family of vascular plants that reproduce by spores rather than seeds. ''Equisetum'' is a "living fossil", the only living genus of the entire subclass Equisetidae, which ...

''"; that is, horsetail) twigs,

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 ...

foliage,

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 comparable with gynomonoecy, andromonoecy and trimonoecy, and contras ...

dioecious Dioecy ( ; ; adj. dioecious, ) is a characteristic of certain species that have distinct unisexual individuals, each producing either male or female gametes, either directly (in animals) or indirectly (in seed plants). Dioecious reproduction is ...

and infructescences ('fruiting bodies') strobiloid or cone-like, meaning combining many outward-pointing valves, each containing a seed, into roughly spherical, cone-like, woody structures. The roots have

nitrogen-fixing Nitrogen fixation is a chemical process by which molecular dinitrogen () is converted into ammonia (). It occurs both biologically and abiological nitrogen fixation, abiologically in chemical industry, chemical industries. Biological nitrogen ...

nodules that contain the soil actinomycete ''

Frankia ''Frankia'' is a genus of nitrogen-fixing bacteria that live in symbiosis with actinorhizal plants, similar to the '' Rhizobium'' bacteria found in the root nodules of legumes in the family Fabaceae. ''Frankia'' also initiate the forming of ro ...

''. In Australia, the most widely used common name for Casuarinaceae species is sheoak or she-oak (a comparison of the timber quality with

English oak ''Quercus robur'', the pedunculate oak, is a species of flowering plant in the beech and oak family, Fagaceae. It is a large tree, native to most of Europe and western Asia, and is widely cultivated in other temperate regions. It grows on soil ...

). Other common names in Australia include ironwood, bull-oak or buloke, beefwood, Cox states that the name 'she-oak' is derived from Native America ''sheac'' — beefwood. or cassowary tree. The

Shire of Buloke The Shire of Buloke is a Local Government Areas of Victoria, local government area in Victoria (Australia), Victoria, Australia, located in the western part of the state. It covers an area of and, in August 2021, had a population of 6,201. It i ...

Victoria, Australia Victoria, commonly abbreviated as Vic, is a state in southeastern Australia. It is the second-smallest state (after Tasmania), with a land area of ; the second-most-populated state (after New South Wales), with a population of over 7 million; ...

, is named after the species ''

Allocasuarina luehmannii ''Allocasuarina luehmannii'', commonly known as buloke or bull-oak, is a species of flowering plant in the family Casuarinaceae and is endemic to south-eastern continental Australia. It is a dioecious tree, that has its leaves reduced to scales ...

''.

Systematics

Modern

molecular phylogenetics Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to ...

suggest the following relationships:

References

External links

* *
Research team
fro
IRD
working on ''

''-Casuarinaceae

mycorrhizal A mycorrhiza (; , mycorrhiza, or mycorrhizas) is a symbiotic association between a fungus and a plant. The term mycorrhiza refers to the role of the fungus in the plant's rhizosphere, the plant root system and its surroundings. Mycorrhizae play ...

and nitrogen-fixing

symbioses Symbiosis (Ancient Greek : living with, companionship < : together; and ''bíōsis'': living) is any type of a close and long-term

Rosid families Taxa named by Robert Brown (botanist, born 1773)