''Austrobaileya'' is the sole genus in the plant family Austrobaileyaceae – the family is thus '

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unisp ...

' as it includes a single child taxon. It is one of the basal angiosperm families, the most ancient group of

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. The genus is also monotypic, containing the single species ''Austrobaileya scandens''. The species is endemic to the Wet Tropics bioregion of

Queensland Queensland ( , commonly abbreviated as Qld) is a States and territories of Australia, state in northeastern Australia, and is the second-largest and third-most populous state in Australia. It is bordered by the Northern Territory, South Austr ...

, Australia, where it occurs in well-developed upland rainforest. It was first described in 1933.

Description

''Austrobaileya'' plants grow as woody lianas or vines. Their main growing stems loosely twine, with straight, extending, leafy branches. The leaves are leathery, veined and simple. The leaves produce

essential oil An essential oil is a concentrated hydrophobic liquid containing volatile (easily evaporated at normal temperatures) chemical compounds from plants. Essential oils are also known as volatile oils, ethereal oils, aetheroleum, or simply as the ...

s in spherical ethereal oil cells. Their foliage is damaged by

oxidation Redox ( , , reduction–oxidation or oxidation–reduction) is a type of chemical reaction in which the oxidation states of the reactants change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is ...

in direct sunlight, so it tends to grow beneath the

rainforest Rainforests are forests characterized by a closed and continuous tree Canopy (biology), canopy, moisture-dependent vegetation, the presence of epiphytes and lianas and the absence of wildfire. Rainforests can be generally classified as tropi ...

canopy, in low-sunlight and very humid conditions. Like many other flowering plants growing in the understory of tropical rainforest, it does not have palisade mesophyll tissue or low leaf photosynthetic rates. It relies strongly on vegetative reproduction for continuation of the species.

''Austrobaileya scandens''

''Austrobaileya scandens'' is a rare species found only (endemic) in the Wet Tropics rainforests of Queensland. It is the oldest species of flowering plants in Australia that requires pollination. ''Austrobaileya'' is one of many ancient (' basal') plants found in Wet Tropics that have survived millions of years of climatic and geological changes. The species is well adapted to rainforests, where it can wind around tall woody trees that form the canopy. It is evolved for fitness in the wet tropical rainforest’s conditions of dampness, humidity, high-light canopy and low-light understory. It can grow up to tall. The plant has a distinctive blue-green colour foliage. ''Austrobaileya'' has large and solitary flowers that are arranged in a spiral with pale green petals. The five or so large sepals are yellowish-green, and larger than the five or so green petals. Flowers are pollinated by

flies Flies are insects of the Order (biology), order Diptera, the name being derived from the Ancient Greek, Greek δι- ''di-'' "two", and πτερόν ''pteron'' "wing". Insects of this order use only a single pair of wings to fly, the hindwin ...

. To attract pollinators, ''A. scandens’'' flowers release a rotting fish smell. Their fruits are apricot-coloured and contain tightly packed

seed In botany, a seed is a plant structure containing an embryo and stored nutrients in a protective coat called a ''testa''. More generally, the term "seed" means anything that can be Sowing, sown, which may include seed and husk or tuber. Seeds ...

s, similar in shape to chestnuts. The fruit is shaped like a

pear Pears are fruits produced and consumed around the world, growing on a tree and harvested in late summer into mid-autumn. The pear tree and shrub are a species of genus ''Pyrus'' , in the Family (biology), family Rosaceae, bearing the Pome, po ...

or eggplant. Fruits have been known to grow to sizes of in length by .

Family Austrobaileyaceae classification

The APG IV system, of 2016 (and the earlier 2009 APG III system and 2003 APG II system), recognise Austrobaileyaceae, placing it in the order Austrobaileyales. Austrobaileyales is accepted as being among the most basal lineages in the clade angiosperms. The Cronquist system, of 1981, assigned the family to the order Magnoliales, in subclass Magnoliidae, in class Magnoliopsida dicotyledons">dicotyledons.html" ;"title="dicotyledons">dicotyledonsof division Magnoliophyta [= angiosperms]. The Thorne system (1992) placed it in the order Magnoliales, which was assigned to superorder Magnolianae, in subclass Magnoliideae dicotyledons in class Magnoliopsida angiosperms The Dahlgren system assigned it to the order Annonales, which was placed in superorder Magnolianae, in subclass Magnoliideae dicotyledons in class Magnoliopsida angiosperms The Engler system, in its update of 1964, assigned it to the order Magnoliales, which was placed in subclass Archychlamydeae in class Dicotyledoneae and in subdivision Angiospermae.

References

External links

picture of fruit

NCBI Taxonomy Browser
{{Taxonbar, from1=Q15712331, from2=Q131513, from3=Q13872246 Austrobaileyales Monotypic angiosperm genera Taxa named by Léon Croizat