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 ...

of dicotyledonous

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, 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, 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''.

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'' in 1980 and 1982, '' Allocasuarina'' 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, this family was the only one placed in the order Verticillatae. Likewise, in the Engler, Cronquist, and Kubitzki systems, the Casuarinaceae were the only family placed in the order Casuarinales. Members of this family are characterized by drooping equisetoid (meaning "looking like '' Equisetum''"; 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''. 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). 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 in

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''.

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 '' Frankia''-Casuarinaceae mycorrhizal and nitrogen-fixing symbioses * * {{Authority control Rosid families Taxa named by Robert Brown (botanist, born 1773)