''Zygochloa'' is a genus of desert plants in the

grass family Poaceae ( ), also called Gramineae ( ), is a large and nearly ubiquitous family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos, the grasses of natural grassland and species cultivated in ...

known only from

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 ...

. The only known species is ''Zygochloa paradoxa'', commonly known as sandhill canegrass. It occurs in extremely arid areas such as the

Simpson Desert The Simpson Desert is a large area of dry, red sandy plain and dunes in the Northern Territory, South Australia and Queensland in central Australia. It is the fourth-largest Deserts of Australia, Australian desert, with an area of . The Wangka ...

.Atlas of Living Australia
/ref>

Description

''Zygochloa paradoxa'' is a dense, green, bushy perennial tall, wide, that forms tussocks or hummocks. Male and female flowers are found on different plants (

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 ...

). The plant has a

rhizomatous In botany and dendrology, a rhizome ( ) is a modified subterranean plant stem that sends out roots and shoots from its nodes. Rhizomes are also called creeping rootstalks or just rootstalks. Rhizomes develop from axillary buds and grow hori ...

stem that usually grows horizontally and has coarse roots . The stem bearing the flowers (

inflorescence In botany, an inflorescence is a group or cluster of flowers arranged on a plant's Plant stem, stem that is composed of a main branch or a system of branches. An inflorescence is categorized on the basis of the arrangement of flowers on a mai ...

), or culm, is hard and brittle with a shallow channel, up to at least in diameter and to tall, cylindrical or somewhat angled. Leaf-blades to long and to wide. There are two types of flowers. The first type are male heads globular in shape, to in diameter. The second type are female heads which are also globular in shape, to in diameter, with the prominent chaffy bract like structures (

bracteoles In botany, a bract is a modified or specialized leaf, associated with a reproductive structure such as a flower, inflorescence axis or cone scale. Bracts are usually different from foliage leaves in size, color, shape or texture. They also look ...

) having rigid tips. Male spikelet with no stem (

sessile Sessility, or sessile, may refer to: * Sessility (motility), organisms which are not able to move about * Sessility (botany), flowers or leaves that grow directly from the stem or peduncle of a plant * Sessility (medicine), tumors and polyps that ...

), to long. Female spikelets are solitary and having a short stem (

pedicellate In botany, a pedicel is a stem that attaches a single flower to the inflorescence. Such inflorescences are described as ''pedicellate''. The stalk at the base of a leaf is called a petiole. Description Pedicel refers to a structure connecti ...

), to long. Flowers mostly March to September.

Taxonomy

''Zygochloa paradoxa'' was first described by the botanist

Robert Brown Robert Brown may refer to: Robert Brown (born 1965), British Director, Animator and author Entertainers and artists * Washboard Sam or Robert Brown (1910–1966), American musician and singer * Robert W. Brown (1917–2009), American printmaker ...

as ''Neurachne paradoxa'' in 1849. The type specimen was collected by

Charles Sturt Charles Napier Sturt (28 April 1795 – 16 June 1869) was a British officer and explorer of Australia, and part of the European land exploration of Australia, European exploration of Australia. He led several expeditions into the interior of the ...

during his expedition into Central Australia (1844 to 1846), and is held by the

Natural History Museum, London The Natural History Museum in London is a museum that exhibits a vast range of specimens from various segments of natural history. It is one of three major museums on Exhibition Road in South Kensington, the others being the Science Museum (Lo ...

. Brown observed that the identification of the species was based on a single specimen which was imperfect in its leaves and stem, however, had sufficient fruits. Brown noted that the specimen differs materially in habit from the original species ''Neurachne alopeuroides'', as well as from ''Neurachne mitchelliana''. No location details were provided, but was likely to have been collected from near the junction of the borders of New South Wales, South Australia and Queensland. In 1874,

Ferdinand von Mueller Baron Sir Ferdinand Jacob Heinrich von Mueller, (; 30 June 1825 – 10 October 1896) was a German-Australian physician, geographer, and most notably, a botanist. He was appointed government botanist for the then colony of Victoria, Australia ...

moved the species to the genus ''Panicum'' and published a replacement name (

nomen novum In biological nomenclature, a ''nomen novum'' (Latin for "new name"), replacement name (or new replacement name, new substitute name, substitute name) is a replacement scientific name that is created when technical, nomenclatural reasons have mad ...

) ''Panicum pseudoneurachne'', on the basis of the smooth hardened fruiting

glume In botany, a glume is a bract (leaf-like structure) below a spikelet in the inflorescence (flower cluster) of grass Poaceae ( ), also called Gramineae ( ), is a large and nearly ubiquitous family (biology), family of monocotyledonous flow ...

and palea. Bentham proposed a new combination ''Spinifex paradoxa'' in 1877. Bentham thought that Mueller had overlooked the dioecious character of the plant, and taking into account the inflorescence being head-shaped (capitate), appeared to belong to the genus ''Spinifex''. However, Bentham did note the discrepancy from ''Spinifex'' due to the small size of spikelets and the lack of long spines. Blake moved the species to a new genus ''Zygochloa'' in 1941, identifying a number of key differences between the plant and ''Spinifex'' genus. Firstly, Blake noted that inflorescences in ''Spinifex'' are less densely head-shaped and considerably larger. Secondly, the extension of the peduncle in ''Spinifex'' into a very long, rigid tapering spine. Finally, in ''Spinifex'' the mature flowers disarticulate in their entirety from the plant, while in ''Zygochloa'' the heads appear to break up. ''Zygochloa paradoxa'' is the current accepted name for the species.

Etymology

When Blake described the genus ''Zygochloa'', he derived the name from Greek ''zygon'' (ζυγόν) meaning pair or yoke, and ''chloa'' (Xλόα) meaning grass. The name refers to the dioecious character of the species. ''Paradoxa'' is from the Greek ''para'' meaning irregular, and ''doxa'' meaning opinion. The plant is different from the expected in regard to related species.

References

{{Taxonbar, from1=Q18822540, from2=Q136988 Panicoideae Poales of Australia Monotypic Poaceae genera Flora of the Northern Territory Flora of New South Wales Flora of Queensland Flora of South Australia Taxa named by Robert Brown (botanist, born 1773)