The Casuarinaceae are a

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Ideall ...

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, t ...

yledonous

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants th ...

s placed in the order

Fagales The Fagales are an order of flowering plants, including some of the best-known trees. The order name is derived from genus ''Fagus'', beeches. They belong among the rosid group of dicotyledons. The families and genera currently included are as ...

, consisting of four

genera Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomencl ...

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 in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...

, Australia,

Southeast Asia Southeast Asia, also spelled South East Asia and South-East Asia, and also known as Southeastern Asia, South-eastern Asia or SEA, is the geographical United Nations geoscheme for Asia#South-eastern Asia, south-eastern region of Asia, consistin ...

Malesia Malesia is a biogeographical region straddling the Equator and the boundaries of the Indomalayan and Australasian realms, and also a phytogeographical floristic region in the Paleotropical Kingdom. It has been given different definitions. The ...

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 the ...

, and the

Pacific Islands Collectively called the Pacific Islands, the islands in the Pacific Ocean 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 se ...

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

Casuarina ''Casuarina'' is a genus of 17 tree species in the family Casuarinaceae, native to Australia, the Indian subcontinent, southeast Asia, islands of the western Pacific Ocean, and eastern Africa. It was once treated as the sole genus in the fam ...

''.

Lawrence Alexander Sidney Johnson Lawrence Alexander Sidney Johnson FAA, (26 June 1925 – 1 August 1997) known as Lawrie Johnson, was an Australian taxonomic botanist. He worked at the Royal Botanic Gardens, Sydney, for the whole of his professional career, as a botanist (1948 ...

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 altitudes having temperate climates, in ...

'' in 1980 and 1982, ''

Allocasuarina ''Allocasuarina'' is a genus of trees in the flowering plant family Casuarinaceae. They are endemic to Australia, occurring primarily in the south. Like the closely related genus ''Casuarina'', they are commonly called sheoaks or she-oaks. W ...

'' 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 cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic gro ...

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

Wettstein system A 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 Synopsis * Flagellatae p. 65 * ...

, 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, snake grass, puzzlegrass) is the only living genus in Equisetaceae, a family of ferns, which reproduce by spores rather than seeds. ''Equisetum'' is a "living fossil", the only living genus of the entire subclass Eq ...

''"; that is, horsetail) twigs,

evergreen In botany, an evergreen is a plant which has foliage that remains green and functional through more than one growing season. This also pertains to plants that retain their foliage only in warm climates, and contrasts with deciduous plants, which ...

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 alongside gynomonoecy, andromonoecy and trimonoecy. Monoecy is conne ...

dioecious Dioecy (; ; adj. dioecious , ) is a characteristic of a species, meaning that it has distinct individual organisms (unisexual) that produce male or female gametes, either directly (in animals) or indirectly (in seed plants). Dioecious reproductio ...

and infructescences ('fruiting bodies') 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 nitrogen (), with a strong triple covalent bond, in the air is converted into ammonia () or related nitrogenous compounds, typically in soil or aquatic systems but also in industry. Atmo ...

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'', commonly known as common oak, pedunculate oak, European oak or English oak, is a species of flowering plant in the beech and oak family, Fagaceae. It is a large tree, native to most of Europe west of the Caucasus. It is wid ...

). 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 area in Victoria, Australia, located in the western part of the state. It covers an area of and, in June 2018, had a population of 6,184. It includes the towns of Birchip, Charlton, Donald, Sea Lake ...

Victoria, Australia Victoria is a state in southeastern Australia. It is the second-smallest state with a land area of , the second most populated state (after New South Wales) with a population of over 6.5 million, and the most densely populated state in A ...

, is named after the species ''

Allocasuarina luehmannii ''Allocasuarina luehmannii'' (buloke or bull-oak) is a species of ironwood tree native to Australia and its wood is the hardest commercially available as measured by the Janka Hardness Scale. Description The evergreen tree typically grows ...

''.

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 (from Greek μύκης ', "fungus", and ῥίζα ', "root"; pl. mycorrhizae, 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 ...

and nitrogen-fixing symbioses * * {{Taxonbar, from=Q474620 Rosid families Taxa named by Robert Brown (botanist, born 1773)