Apostasia orchid
Encyclopedia
Apostasia is a genus
of primitive orchids (family
Orchidaceae), comprising 7 terrestrial species
.
The genus is distributed in humid areas of the Himalayan region, India
, Sri Lanka
, New Guinea
, and North Australia
.
The species of Apostasia produce an erect inflorescence with up to six lateral branches, arising from the main, elongated root. Their warty tubercle
s are swollen and stalked. They lack velamen
.
They bear up to 30 white or yellow flower
s. The flowers of Apostasia species are non-resupinate (i. e. not turned upside down), as in the other orchids.
Like Neuwiedia
with 3 fertile stamens, the other genus of the same subfamily, Apostasia is noted for having 2 fertile, abaxial stamen
s instead of one like other orchids. The possession of 2-3 abaxial anthers is autapomorphous (= a derived characteristic unique to a taxon
) in the Apostasioideae
. Apostasia nuda, Apostasia elliptica and Apostasia latifolia lack a staminode
. This loss of a staminode is an apomorphy (= derived characteristic). The other species are characterized by a staminode that is homologous to the only stamen
of monandrous orchids. This presence of a staminode defines an ancestral trait (= plesiomorphic).
Because of that primitive feature, some authority did not consider Apostasia as real orchids. Nevertheless the difference between these genera and outgroups in cladistic
analysis is larger than with the rest of the orchids. They are therefore included within the orchid family.
The genera Adactylus Rolfe
and Mesodactylis Wall.
, Neumayera Rchb.f
and Niemeyera F.Muell. have been brought into synonymy with Apostasia.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of primitive orchids (family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Orchidaceae), comprising 7 terrestrial species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
.
The genus is distributed in humid areas of the Himalayan region, India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
, Sri Lanka
Sri Lanka
Sri Lanka, officially the Democratic Socialist Republic of Sri Lanka is a country off the southern coast of the Indian subcontinent. Known until 1972 as Ceylon , Sri Lanka is an island surrounded by the Indian Ocean, the Gulf of Mannar and the Palk Strait, and lies in the vicinity of India and the...
, New Guinea
New Guinea
New Guinea is the world's second largest island, after Greenland, covering a land area of 786,000 km2. Located in the southwest Pacific Ocean, it lies geographically to the east of the Malay Archipelago, with which it is sometimes included as part of a greater Indo-Australian Archipelago...
, and North Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
.
The species of Apostasia produce an erect inflorescence with up to six lateral branches, arising from the main, elongated root. Their warty tubercle
Tubercle
A tubercle is generally a wart-like projection, but it has slightly different meaning depending on which family of plants or animals it is used to refer to....
s are swollen and stalked. They lack velamen
Velamen
Velamen is a spongy, multiple epidermis that covers the roots of some epiphytic or semi-epiphytic plants, such as orchid and Clivia species....
.
They bear up to 30 white or yellow flower
Flower
A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants . The biological function of a flower is to effect reproduction, usually by providing a mechanism for the union of sperm with eggs...
s. The flowers of Apostasia species are non-resupinate (i. e. not turned upside down), as in the other orchids.
Like Neuwiedia
Neuwiedia
Neuwiedia is a genus of primitive orchids , comprising 9 terrestrial species.The type species is Neuwiedia veratrifolia Blume 1834...
with 3 fertile stamens, the other genus of the same subfamily, Apostasia is noted for having 2 fertile, abaxial stamen
Stamen
The stamen is the pollen producing reproductive organ of a flower...
s instead of one like other orchids. The possession of 2-3 abaxial anthers is autapomorphous (= a derived characteristic unique to a taxon
Taxon
|thumb|270px|[[African elephants]] form a widely-accepted taxon, the [[genus]] LoxodontaA taxon is a group of organisms, which a taxonomist adjudges to be a unit. Usually a taxon is given a name and a rank, although neither is a requirement...
) in the Apostasioideae
Apostasioideae
In plant systematics Apostasioideae is one of the five subfamilies recognised within the orchid family, Orchidaceae. Only two genera, Neuwidia and Apostasia and 15 species are recognised within the Apostasioideae in contrast to the other orchid subfamilies which are highly speciose.The...
. Apostasia nuda, Apostasia elliptica and Apostasia latifolia lack a staminode
Staminode
In botany, a staminode is an often rudimentary, sterile or abortive stamen. This means that it does not produce pollen. Staminodes are frequently inconspicuous and stamen-like, usually occurring at the inner whorl of the flower, but are also sometimes long enough to protrude from the...
. This loss of a staminode is an apomorphy (= derived characteristic). The other species are characterized by a staminode that is homologous to the only stamen
Stamen
The stamen is the pollen producing reproductive organ of a flower...
of monandrous orchids. This presence of a staminode defines an ancestral trait (= plesiomorphic).
Because of that primitive feature, some authority did not consider Apostasia as real orchids. Nevertheless the difference between these genera and outgroups in cladistic
Cladistics
Cladistics is a method of classifying species of organisms into groups called clades, which consist of an ancestor organism and all its descendants . For example, birds, dinosaurs, crocodiles, and all descendants of their most recent common ancestor form a clade...
analysis is larger than with the rest of the orchids. They are therefore included within the orchid family.
The genera Adactylus Rolfe
Robert Allen Rolfe
Robert Allen Rolfe was a British botanist specializing in the study of orchids. He was the first curator of the orchid herbarium at the Royal Botanic Gardens, Kew, founded the magazine The Orchid Review,and published many papers on hybrids of different species of orchids.The genus Allenrolfea of...
and Mesodactylis Wall.
Nathaniel Wallich
Nathaniel Wallich was a surgeon and botanist of Danish origin who worked in India initially in the Danish settlement near Calcutta and later joined the East India Company...
, Neumayera Rchb.f
Heinrich Gustav Reichenbach
Heinrich Gustav Reichenbach was an ornithologist, botanist and the foremost German orchidologist of the 19th century...
and Niemeyera F.Muell. have been brought into synonymy with Apostasia.
Species
- Apostasia elliptica J.J.Sm., 1920.
- Apostasia latifolia Rolfe, 1889.
- Apostasia nudaApostasia nudaApostasia nuda is a species of orchid....
R.Br. in N.Wallich, 1830. - Apostasia odorata Blume, 1825.
- Apostasia parvula Schltr., 1906.
- Apostasia ramifera S.C.Chen & K.Y.Lang, 1986.
- Apostasia wallichiiApostasia wallichiiApostasia wallichii is a species of orchid....
R.Br. in N.Wallich, 1830.