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''Idiospermum'' is a
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 ...
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 ...
(that is, a genus that contains only one species) in the family
Calycanthaceae The Calycanthaceae (sweetshrubs or spicebushes) are a small family of flowering plants in the order Laurales. The family contains three genera and only 10 known species , restricted to warm temperate and tropical regions: They are aromatic, d ...
. The sole included species is ''Idiospermum australiense'' − commonly known as idiotfruit, ribbonwood, or dinosaur tree − which is found only in two small areas of the tropical rainforests of northeastern
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. It is a relic of the ancient forests of
Gondwana Gondwana ( ; ) was a large landmass, sometimes referred to as a supercontinent. The remnants of Gondwana make up around two-thirds of today's continental area, including South America, Africa, Antarctica, Australia (continent), Australia, Zea ...
, surviving in very localised refugia for 120 million years, and displaying features (of the flowers in particular) that are almost identical to fossil records from that time. As such it provides an important insight into the very early evolution 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.


Description

''Idiospermum australiense'' has, in contrast to its weighty evolutionary significance and its extraordinarily unique fruit, a rather nondescript overall appearance. It is a broadleaf
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 ...
tree growing to around tall, with a maximum trunk
diameter at breast height Diameter at breast height, or DBH, is a standard method of expressing the diameter of the trunk or bole of a standing tree. DBH is one of the most common dendrometric measurements. Tree trunks are measured at the height of an adult's breast, ...
(DBH) of around . The leaves are
simple Simple or SIMPLE may refer to: *Simplicity, the state or quality of being simple Arts and entertainment * ''Simple'' (album), by Andy Yorke, 2008, and its title track * "Simple" (Florida Georgia Line song), 2018 * "Simple", a song by John ...
(without lobes or divisions),
opposite In lexical semantics, opposites are words lying in an inherently incompatible binary relationship. For example, something that is ''even'' entails that it is not ''odd''. It is referred to as a 'binary' relationship because there are two members i ...
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, ...
(without hairs). They measure up to long by wide, with 7−10 pairs of lateral veins. They are held on petioles measuring long, and the leaf blades exhibit numerous 'oil dots' or pellucid glands (tiny, translucent spots) when held up against a strong light source.


Flowers

The flowers may be solitary or in a
panicle In botany, a panicle is a much-branched inflorescence. (softcover ). Some authors distinguish it from a compound spike inflorescence, by requiring that the flowers (and fruit) be pedicellate (having a single stem per flower). The branches of a p ...
, produced either terminally or in the leaf
axils A leaf (: leaves) is a principal appendage of the stem of a vascular plant, usually borne laterally above ground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, stem, f ...
. They are sessile (without a stem) and measure about wide when fully open. All floral organs −
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 ...
s,
tepal A tepal is one of the outer parts of a flower (collectively the perianth). The term is used when these parts cannot easily be classified as either sepals or petals. This may be because the parts of the perianth are undifferentiated (i.e. of very ...
s,
stamen The stamen (: stamina or stamens) is a part consisting of the male reproductive organs of a flower. Collectively, the stamens form the androecium., p. 10 Morphology and terminology A stamen typically consists of a stalk called the filament ...
s,
staminode In botany, a staminode is an often rudimentary, sterile or abortive stamen, which means that it does not produce pollen.Jackson, Benjamin, Daydon; ''A Glossary of Botanic Terms with their Derivation and Accent''; Published by Gerald Duckworth & Co ...
s and
carpel Gynoecium (; ; : gynoecia) is most commonly used as a collective term for the parts of a flower that produce ovules and ultimately develop into the fruit and seeds. The gynoecium is the innermost whorl of a flower; it consists of (one or more ...
s − are spirally arranged and there is no clear distinction between sepals and petals. The tepals are numerous with up to 52 per flower. The stamens number 13 to 15, and arch forward over the opening of the floral cup; the stigma lies well below the stamens and staminodes. The morphology of the
gynoecium Gynoecium (; ; : gynoecia) is most commonly used as a collective term for the parts of a flower that produce ovules and ultimately develop into the fruit and seeds. The gynoecium is the innermost whorl (botany), whorl of a flower; it consists ...
(the female parts of the flower that receive pollen and produce fruit) seen in the populations north of the Daintree River differ from that seen in populations south of Cairns (see Distribution and habitat). More than half of those in the north have been found to lack
carpels Gynoecium (; ; : gynoecia) is most commonly used as a collective term for the parts of a flower that produce ovules and ultimately develop into the fruit and seeds. The gynoecium is the innermost whorl of a flower; it consists of (one or more) ...
(the structure that contains the ovary), and the remainder have one or (very rarely) two carpels. On the other hand, all those from the south have at least one carpel, most have two, and some have up to five.


Fruit

The fruit is, in botanical terms, a
berry A berry is a small, pulpy, and often edible fruit. Typically, berries are juicy, rounded, brightly colored, sweet, sour or tart, and do not have a stone or pit although many pips or seeds may be present. Common examples of berries in the cul ...
(a fruit derived from a single ovary of a single flower), but in which all the layers surrounding the
embryo An embryo ( ) is the initial stage of development for a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male sp ...
− including the layers that, in other species, would form the fleshy outer layers and even the hard exterior coating of the seed − decay while still on the parent tree. What then falls from the tree is just the extremely large naked plant embryo, measuring roughly high and diameter). This is the largest embryo of any flowering plant. Another unique feature of the ribbonwood is the fact that the fruit contain multiple
cotyledon A cotyledon ( ; ; "a cavity, small cup, any cup-shaped hollow", gen. (), ) is a "seed leaf" – a significant part of the embryo within the seed of a plant – and is formally defined as "the embryonic leaf in seed-bearing plants, one or mor ...
s (embryonic leaves within the seed). All other
flowering plants 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 ...
have either
one 1 (one, unit, unity) is a number, numeral, and glyph. It is the first and smallest positive integer of the infinite sequence of natural numbers. This fundamental property has led to its unique uses in other fields, ranging from science to sp ...
or two cotyledons.


Phenology

Flowering of the ribbonwood occurs from early May through to mid June in the southern populations, and from June to mid September in the northern populations. The species is dichogamous, that is the flowers are initially functionally female and then become functionally male. The flowers have a lifespan of between 10 and 16 days. Initially, the
stamen The stamen (: stamina or stamens) is a part consisting of the male reproductive organs of a flower. Collectively, the stamens form the androecium., p. 10 Morphology and terminology A stamen typically consists of a stalk called the filament ...
s and staminodes (sterile appendages between the stamens and the carpel) which surround the stigma are held back, allowing access to the stigma and potential pollination. After 2−3 days the stamens start to close in, blocking access to the stigma. At the same time the
anther The stamen (: stamina or stamens) is a part consisting of the male reproductive organs of a flower. Collectively, the stamens form the androecium., p. 10 Morphology and terminology A stamen typically consists of a stalk called the filament ...
s open, at which point the flower becomes functionally male. The tepals change colour during this process, being a creamy white when the flower first opens and darkening to red by the end of the process. At any point in time during the flowering period, a tree may have flowers in a various stages of development.


Taxonomy

This species was originally described in 1912 as ''Calycanthus australiensis'' by the German botanist
Ludwig Diels Friedrich Ludwig Emil Diels (24 September 1874 – 30 November 1945) was a German botanist. Diels was born in Hamburg, the son of the classical scholar Hermann Alexander Diels. From 1900 to 1902 he traveled together with Ernst Georg Pritzel thro ...
, based on material he collected himself in 1902. He arrived in the area in June, a month that is now known as the peak of the flowering season for this species, but he was apparently ill-prepared and was only able to collect flowers that had already fallen to the ground as well as a leafy branch. His paper, titled ''Über primitive Ranales der australischen Flora'', was published in the journal ''Botanische Jahrbücher für Systematik, Pflanzengeschichte und Pflanzengeographie'', some ten years after he collected the specimens. In the prologue to his description he lamented that it was incomplete, as he had not found a specimen of the fruit, nor flowers from the canopy. He also commented that the lack of a complete set of specimens is why he waited ten years before writing the description. It was not until 1972 that a complete description was published by the Australian botanist
Stanley Thatcher Blake Stanley Thatcher Blake (1910 – 24 February 1973) was an Australian botanist who served as president of the Royal Society of Queensland and who was associated with the Queensland Herbarium beginning in 1945 until his death. Background Prior to ...
in the journal Contributions from the Queensland Herbarium. At the time Blake erected a new family − Idiospermaceae − for this taxon, but it is now widely accepted as belonging to the family
Calycanthaceae The Calycanthaceae (sweetshrubs or spicebushes) are a small family of flowering plants in the order Laurales. The family contains three genera and only 10 known species , restricted to warm temperate and tropical regions: They are aromatic, d ...
The original
holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...
(i.e. the specimen of plant material collected and used to create the description) for this species was collected by Diels and taken to Berlin. In 1943 it was destroyed in a bombing raid, and a replacement (neotype) had to be chosen. This did not come about until the species was rediscovered, and the sample chosen was collected by the Australian botanist Stuart Worboys in 1998, from the same locality as the original.


Etymology

The name ''Idiospermum'' derives from the Ancient Greek words ''idios'' meaning "individuality" or "peculiarity", and ''spérma'' meaning "seed", and is a reference to the unique characteristics of the fruits. The common name "idiot fruit" is a mistranslation of this.


Distribution and habitat

The area occupied by the populations of ''Idiospermum australiense'' is a total of just There are two main populations, the first (where Diels collected his samples), is approximately south of
Cairns Cairns (; ) is a city in the Cairns Region, Queensland, Australia, on the tropical north east coast of Far North Queensland. In the , Cairns had a population of 153,181 people. The city was founded in 1876 and named after William Cairns, Sir W ...
, in the vicinity of the Russell River and its tributaries. The other is approximately north of Cairns and around south of
Cape Tribulation Cape Tribulation is a headland and coastal locality in the Shire of Douglas in northern Queensland, Australia. In the , Cape Tribulation had a population of 123 people. Geography The locality is north of Cairns. It is within the Daintree N ...
, in the areas of Cooper and Noah Creeks. Both areas are rainforested lowlands at the foot of high, rain-attracting mountains, with annual rainfalls of more than , and alluvial soils. As the seeds of ribbonwood are only dispersed by gravity, the distribution of the species can only expand seawards.


Ecology

Due to the enormous size of the seeds there are no animals that eat them and subsequently disperse them. Even the
cassowary Cassowaries (; Biak: ''man suar'' ; ; Papuan: ''kasu weri'' ) are flightless birds of the genus ''Casuarius'', in the order Casuariiformes. They are classified as ratites, flightless birds without a keel on their sternum bones. Cassowaries a ...
, well-known for its ability to swallow large fruit, does not eat these. They are also known to be extremely toxic to cattle (see Discovery, loss and re-discovery) and probably to other animals as well. A large variety of insects, mostly beetles and thrips, are attracted by the scent and colour of the flower, and they in turn attract predators such as spiders and ants. Only the beetles and thrips appear to take a role in pollination, which is completed only when an insect first visits a flower in the male phase and then carries pollen to a flower in the female phase.


Discovery, loss and re-discovery

The first European-Australians to encounter this tree were timber cutters working the lowland forests between Innisfail and
Cairns Cairns (; ) is a city in the Cairns Region, Queensland, Australia, on the tropical north east coast of Far North Queensland. In the , Cairns had a population of 153,181 people. The city was founded in 1876 and named after William Cairns, Sir W ...
in the late 1800s. Word of their discovery caught the attention of the German botanist
Ludwig Diels Friedrich Ludwig Emil Diels (24 September 1874 – 30 November 1945) was a German botanist. Diels was born in Hamburg, the son of the classical scholar Hermann Alexander Diels. From 1900 to 1902 he traveled together with Ernst Georg Pritzel thro ...
, who ventured to the area in 1902 to collect specimens. He found one tree in flower but was unable to collect fresh flowers as they are produced high in the canopy. Instead he collected fallen flowers, a leafy twig, but crucially no fruit. He took the samples back to Berlin with him, and in his disappointment about the incomplete collection, forgot about the material for years. By the time Diels published his paper (in which he noted that the species was rare and that he had the only known collections) the lowland forests where he found it were being cleared for
sugar cane Sugarcane or sugar cane is a species of tall, Perennial plant, perennial grass (in the genus ''Saccharum'', tribe Andropogoneae) that is used for sugar Sugar industry, production. The plants are 2–6 m (6–20 ft) tall with stout, jointed, fib ...
farming, and were gone by the 1920s. For the next 60 years the species was thought to have been lost. In 1971 a grazier by the name of John Nicholas, who had a property in farmland in the Cow Bay area north of the Daintree River, discovered some of his cattle had died unexpectedly after suffering spasms. Believing someone had poisoned them he called in the police. A government veterinarian, Doug Clague, examined the beasts and found large, unknown seeds in their stomachs, which appeared to have fallen from a particular tree on the property. He sent the "seeds" and some flowers from the tree to the
Queensland Herbarium The Queensland Herbarium (Index Herbariorum code: BRI) is situated at the Brisbane Botanic Gardens, Mount Coot-tha, in Brisbane, Queensland, Australia. It is part of Queensland's Department of Environment and Science. It is responsible for disc ...
for identification. There, the botanist
Stanley Thatcher Blake Stanley Thatcher Blake (1910 – 24 February 1973) was an Australian botanist who served as president of the Royal Society of Queensland and who was associated with the Queensland Herbarium beginning in 1945 until his death. Background Prior to ...
, on seeing the flowers, suspected that they were from the long lost ''Calycanthus australiensis'' (as it was still known at the time). Blake was eager to undertake a detailed study of the plant and visited the property himself a short time after, where he collected material from both the farm and from remnant forest along a nearby creek. More specimens were collected by others, including Len Webb and Geoff Tracey of the
CSIRO The Commonwealth Scientific and Industrial Research Organisation (CSIRO) is an Australian Government agency that is responsible for scientific research and its commercial and industrial applications. CSIRO works with leading organisations arou ...
Rainforest Ecology Research Unit, and also Bernard Hyland from the Commonwealth Forestry and Timber Bureau in Atherton, who all collected material in the area of Noah Creek, the only other watershed between Cow Bay and Cape Tribulation. Upon closer inspection of the fruit and the flower specimens together, along with details of the size of the tree, it soon became apparent to Blake that this was not a species of ''Calycanthus'', and he raised a new genus, ''Idiospermum'', to accommodate it.


Conservation

Although this species has a very restricted range and has lost much of its former habitat, the remaining areas in which it occurs are now protected. Accordingly it is listed by the Queensland Department of Environment and Science as
least concern A least-concern species is a species that has been evaluated and categorized by the International Union for Conservation of Nature (IUCN) as not being a focus of wildlife conservation because the specific species is still plentiful in the wil ...
. , it has not been assessed by the
International Union for Conservation of Nature The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the stat ...
(IUCN).


Gallery

File:Gardenology.org-IMG 0431 rbgs10dec.jpg,
Royal Botanic Gardens, Sydney The Royal Botanic Garden, Sydney is a heritage-listed major botanical garden, event venue and public recreation area located at Farm Cove on the eastern fringe of the Sydney central business district, in the City of Sydney local government are ...
, Dec 2010 File:Idiospermum-australiense-SF23097-01.jpg, Foliage,
Cairns Botanic Gardens Flecker Botanic Gardens is a heritage-listed botanic garden at Collins Avenue, Edge Hill, Queensland, Edge Hill, Queensland, Australia. It was built from 1886 to 1960s. It is now known as Cairns Botanic Gardens. It was added to the Queensland ...
, April 2023 File:Idiospermum-australiense-SF23097-04.jpg, Twig and leaves,
Cairns Botanic Gardens Flecker Botanic Gardens is a heritage-listed botanic garden at Collins Avenue, Edge Hill, Queensland, Edge Hill, Queensland, Australia. It was built from 1886 to 1960s. It is now known as Cairns Botanic Gardens. It was added to the Queensland ...
, April 2023 File:Idiospermum australiense 44967538.jpg, Multiple seedlings from a single "fruit" File:Idiospermum-australiense-SF23097-07.jpg,
Cairns Botanic Gardens Flecker Botanic Gardens is a heritage-listed botanic garden at Collins Avenue, Edge Hill, Queensland, Edge Hill, Queensland, Australia. It was built from 1886 to 1960s. It is now known as Cairns Botanic Gardens. It was added to the Queensland ...
, April 2023


References


External links

* *
The story of the rediscovery of the Idiospermum
by local resident Prue Hewett
View a map
of historical sightings of this species at the
Australasian Virtual Herbarium The ''Australasian Virtual Herbarium'' (AVH) is an online resource that allows access to plant specimen data held by various Australian and New Zealand herbaria. It is part of the Atlas of Living Australia (ALA), and was formed by the amalgama ...

View observations
of this species on
iNaturalist iNaturalist is an American 501(c)(3) nonprofit social network of naturalists, citizen scientists, and biologists built on the concept of mapping and sharing observations of biodiversity across the globe. iNaturalist may be accessed via its web ...

View images
of this species on Flickriver {{Taxonbar, from1=Q134589, from2=Q5908811 Flora of Queensland Laurales of Australia Monotypic Laurales genera Calycanthaceae