''Praecoxanthus aphyllus'', commonly known as leafless orchid, is the only species of the

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 ...

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

''Praecoxanthus'' in the orchid

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 ...

Orchidaceae Orchids are plants that belong to the family (biology), family Orchidaceae (), a diverse and widespread group of flowering plants with blooms that are often colourful and fragrant. Orchids are cosmopolitan distribution, cosmopolitan plants that ...

and is endemic to the south-west of

Western Australia Western Australia (WA) is the westernmost state of Australia. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to the south, the Northern Territory to the north-east, and South Australia to the south-east. Western Aust ...

. Plants in flower lack a true leaf, although those plants that are not flowering do possess a green leaf. This species is one of the first orchids to flower each year and its creamy white, fragrant flower easily distinguishes it from other species.

Description

''Praecoxanthus aphyllus'' is a terrestrial,

perennial In horticulture, the term perennial ('' per-'' + '' -ennial'', "through the year") is used to differentiate a plant from shorter-lived annuals and biennials. It has thus been defined as a plant that lives more than 2 years. The term is also ...

deciduous In the fields of horticulture and botany, the term deciduous () means "falling off at maturity" and "tending to fall off", in reference to trees and shrubs that seasonally shed Leaf, leaves, usually in the autumn; to the shedding of petals, aft ...

sympodial In botany, sympodial growth is a bifurcating branching pattern where one branch develops more strongly than the other, resulting in the stronger branches forming the primary shoot and the weaker branches appearing laterally. A sympodium, als ...

herb Herbs are a widely distributed and widespread group of plants, excluding vegetables, with savory or aromatic properties that are used for flavoring and garnishing food, for medicinal purposes, or for fragrances. Culinary use typically distingu ...

with a few inconspicuous, fine roots and a

tuber Tubers are a type of enlarged structure that plants use as storage organs for nutrients, derived from stems or roots. Tubers help plants perennate (survive winter or dry months), provide energy and nutrients, and are a means of asexual reproduc ...

partly surrounded by a fibrous sheath. The tuber produces a replacement "dropper" which becomes the daughter tuber in the following year. Non-flowering plants produce a single, stalkless, egg-shaped leaf which is long, wide and

glabrous Glabrousness () is the technical term for a lack of hair, down, setae, trichomes, or other such covering. A glabrous surface may be a natural characteristic of all or part of a plant or animal, or be due to loss because of a physical condition, ...

with prominent white veins. The leaf of flowering plants is reduced to a tiny

bract 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 lo ...

at the base of the stem. There is a single resupinate flower on the end of a wiry, glabrous stem high. The flower is wide and long. The three

sepal A sepal () is a part of the flower of angiosperms (flowering plants). Usually green, sepals typically function as protection for the flower in bud, and often as support for the petals when in bloom., p. 106 Etymology The term ''sepalum'' ...

s and two

petal Petals are modified leaves that form an inner whorl surrounding the reproductive parts of flowers. They are often brightly coloured or unusually shaped to attract pollinators. All of the petals of a flower are collectively known as the ''corol ...

s are spreading, creamy-white, free and similar in size and shape to each other. As is usual in orchids, one petal is highly modified as the central labellum. The labellum has three lobes and is purple, green and yellow with two irregular rows of stalked, club-like calli. The sexual parts of the flower are fused to the

column A column or pillar in architecture and structural engineering is a structural element that transmits, through compression, the weight of the structure above to other structural elements below. In other words, a column is a compression member ...

, which has wing-like structures on its sides and are widest at the base. Flowering occurs from March to May and the fruit that follows is a non-fleshy, hairy,

dehiscent Dehiscence is the splitting of a mature plant structure along a built-in line of weakness to release its contents. This is common among fruits, anthers and sporangia. Sometimes this involves the complete detachment of a part. Structures that op ...

capsule containing a large number of seeds.

Taxonomy and naming

Leafless orchid was first formally described in 1837 by

George Bentham George Bentham (22 September 1800 – 10 September 1884) was an English botanist, described by the weed botanist Duane Isely as "the premier systematic botanist of the nineteenth century". Born into a distinguished family, he initially studie ...

who gave it the name ''Caladenia aphylla'' and published the description in ''

Flora Australiensis ''Flora Australiensis: a description of the plants of the Australian Territory'', more commonly referred to as ''Flora Australiensis'', and also known by its standard abbreviation ''Fl. Austral.'', is a seven-volume Flora of Australia published b ...

''. In 2000,

Stephen Hopper Stephen Donald Hopper (born 18 June 1951) is a Western Australian botanist. He graduated in Biology, specialising in conservation biology and vascular plants. Hopper has written eight books, and has over 200 publications to his name. He was Direc ...

and Andrew Brown described the genus ''Praecoxanthus'' and included this species. The genus name ''"Praecoxanthus"'' is derived from the

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

word ''praecox'' meaning "premature" or "precocious" and the

Ancient Greek Ancient Greek (, ; ) includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Greek ...

''anthos'' meaning "flower". The

specific epithet In Taxonomy (biology), taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin gramm ...

"aphyllus" is derived from the

prefix "a-" meaning "without" and ''phyllon'' meaning "leaf".

Ecology

Leafless orchid flowers are highly fragrant and attract native bees. The yellow calli on a purple labellum resemble pollen-bearing stamens but the flower is nectarless, attracting the insects to an absent reward.

Distribution and habitat

This orchid usually grows in sandy soils in woodland but near Esperance tends to grow in low heath with sub-soil moisture. Unlike some orchids, they do not usually grow in colonies and individuals are well-spaced. It occurs between Pinjarra and Albany and in a coastal strip east to Esperance in the

Avon Wheatbelt The Avon Wheatbelt is a bioregion in Western Australia. It has an area of . It is considered part of the larger Southwest Australia savanna ecoregion. Geography The Avon Wheatbelt bioregion is mostly a gently undulating landscape with low rel ...

Esperance Plains Esperance Plains, also known as Eyre Botanical District, is a biogeography, biogeographic region in southern Western Australia on the South_coast_of_Western_Australia , south coast between the Avon Wheatbelt and Hampton bioregions, and bordere ...

Jarrah Forest Jarrah Forest, also known as the Southwest Australia woodlands, is an interim Australian bioregion and ecoregion located in the south west of Western Australia.

, Mallee,

Swan Coastal Plain The Swan Coastal Plain in Western Australia is the geographic feature which contains the Swan River as it travels west to the Indian Ocean. The coastal plain continues well beyond the boundaries of the Swan River and its tributaries, as a geol ...

and

Warren Warren most commonly refers to: * Warren (burrow), a network dug by rabbits * Warren (name), a given name and a surname, including lists of persons so named Warren may also refer to: Places Australia * Warren (biogeographic region) * War ...

biogeographic regions.

Conservation

''Praecoxanthus aphyllus'' is classified as "Not Threatened" by the Western Australian Government

Department of Parks and Wildlife The Department of Parks and Wildlife (DPaW) was the department of the Government of Western Australia responsible for managing lands described in the ''Conservation and Land Management Act 1984'' and implementing the state's conservation and en ...

References

External links

* *
C Hookman, ''Praecoxanthus aphyllus'' - Leafless Orchid
{{Taxonbar, from1=Q9062096, from2=Q15515349 Monotypic Orchidoideae genera Diurideae genera Caladeniinae Orchids of Western Australia