Idiospermum
Encyclopedia
Idiospermum australiense, the sole species in the genus Idiospermum, is one of the most primitive flowering plant
s known, having lived in the Daintree Rainforest
of Queensland
, Australia
for 120 million years. It is only found in very few locations of the Daintree Rainforest in the very wet lowland parts of the forest, where it grows in groups of 10-100 trees together (rather than scattered individuals). Common names include Ribbonwood and Idiot Fruit.
It is an evergreen
tree
, growing to 20–30 m tall. The leaves
are produced singly, in pairs or in whorls of 3-4; the leaf is simple, 12–25 cm long and 5–9 cm broad. The flower
s are 4–5 cm diameter, with spirally arranged red petal
s. The fruit
is a brittle globular nut
-like seed
around 8 cm in diameter, which splits into three or four segments once fallen; it is very toxic, with symptoms (in cattle
) similar to strychnine
.
Most plants have both male and female sex organs, but half of the flower
s of the Ribbonwood do not obtain any female sex organs, the species using the process of cross-pollination. Attracted by the colour and smell of the flower, tiny beetle
s and thrips crawl in and lay their eggs within the center of the flower, which contains the flower's pollen
. Within the flower some of the sticky pollen gets trapped on the insect's bodies, and if the next flower they visit is a receptive one, it will pollinate
and produce the seeds.
While other modern flowering plants produce seeds which have one cotyledon
(monocotyledon
s) or two (dicotyledon
s), the seedlings of the Ribbonwood have between three or four cotyledons. Also the Ribbonwood can produce more than one shoot per seed, while the seeds in all other plant species will develop and send up a single shoot.
The seeds are currently mainly spread through gravity dispersal, the seeds rolling down the steep mountain slopes to find their new home. The seeds are so toxic that most animals cannot eat them; however it is known that the native Musky Rat-kangaroo does disperse and bury some of these seeds. It has been suggested that the seeds were formerly dispersed by the now-extinct Diprotodon
, on the basis that many Australian marsupials are adapted to cope with the toxins in Australian plants.
The plants have adapted a unique poison, a chemical called Idiospermuline contained within the seed, to prevent animals eating them. Researchers discovered the poison affects transmission of messages between individual nerve cells, which may cause seizures. In small doses this chemical can be used to save lives.
, who described the species in the genus Calycanthus
as C. australiense in 1902, a remarkable disjunction for this otherwise North America
n genus. It was later believed to be extinct again, because when Diels finally returned to the location where this tree was found, the area had been cleared for a sugar cane farm.
The species was re-rediscovered in 1971, after the poison
ous seeds of the plant were found in the stomachs of dying cattle in the region. In 1972, the Australian botanist T. S. Blake reassigned it to the new family Idiospermaceae and the genus
Idiospermum (idio-, "unusual", and spermum, "seed"). In its 2003 revision, the Angiosperm Phylogeny Group
retained it in the new genus, but restored the species to the family Calycanthaceae
.
Flowering plant
The flowering plants , also known as Angiospermae or Magnoliophyta, are the most diverse group of land plants. Angiosperms are seed-producing plants like the gymnosperms and can be distinguished from the gymnosperms by a series of synapomorphies...
s known, having lived in the Daintree Rainforest
Daintree Rainforest
The Daintree Rainforest is a tropical rainforest on the north east coast of Queensland, Australia, north of Mossman and Cairns. At around 1200 square kilometres the Daintree is the largest continuous area of tropical rainforest on the Australian continent...
of Queensland
Queensland
Queensland is a state of Australia, occupying the north-eastern section of the mainland continent. It is bordered by the Northern Territory, South Australia and New South Wales to the west, south-west and south respectively. To the east, Queensland is bordered by the Coral Sea and Pacific Ocean...
, 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...
for 120 million years. It is only found in very few locations of the Daintree Rainforest in the very wet lowland parts of the forest, where it grows in groups of 10-100 trees together (rather than scattered individuals). Common names include Ribbonwood and Idiot Fruit.
It is an evergreen
Evergreen
In botany, an evergreen plant is a plant that has leaves in all seasons. This contrasts with deciduous plants, which completely lose their foliage during the winter or dry season.There are many different kinds of evergreen plants, both trees and shrubs...
tree
Tree
A tree is a perennial woody plant. It is most often defined as a woody plant that has many secondary branches supported clear of the ground on a single main stem or trunk with clear apical dominance. A minimum height specification at maturity is cited by some authors, varying from 3 m to...
, growing to 20–30 m tall. The leaves
Leaf
A leaf is an organ of a vascular plant, as defined in botanical terms, and in particular in plant morphology. Foliage is a mass noun that refers to leaves as a feature of plants....
are produced singly, in pairs or in whorls of 3-4; the leaf is simple, 12–25 cm long and 5–9 cm broad. The 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 are 4–5 cm diameter, with spirally arranged red petal
Petal
Petals are modified leaves that surround the reproductive parts of flowers. They often are brightly colored or unusually shaped to attract pollinators. Together, all of the petals of a flower are called a corolla. Petals are usually accompanied by another set of special leaves called sepals lying...
s. The fruit
Fruit
In broad terms, a fruit is a structure of a plant that contains its seeds.The term has different meanings dependent on context. In non-technical usage, such as food preparation, fruit normally means the fleshy seed-associated structures of certain plants that are sweet and edible in the raw state,...
is a brittle globular nut
Nut (fruit)
A nut is a hard-shelled fruit of some plants having an indehiscent seed. While a wide variety of dried seeds and fruits are called nuts in English, only a certain number of them are considered by biologists to be true nuts...
-like seed
Seed
A seed is a small embryonic plant enclosed in a covering called the seed coat, usually with some stored food. It is the product of the ripened ovule of gymnosperm and angiosperm plants which occurs after fertilization and some growth within the mother plant...
around 8 cm in diameter, which splits into three or four segments once fallen; it is very toxic, with symptoms (in cattle
Cattle
Cattle are the most common type of large domesticated ungulates. They are a prominent modern member of the subfamily Bovinae, are the most widespread species of the genus Bos, and are most commonly classified collectively as Bos primigenius...
) similar to strychnine
Strychnine
Strychnine is a highly toxic , colorless crystalline alkaloid used as a pesticide, particularly for killing small vertebrates such as birds and rodents. Strychnine causes muscular convulsions and eventually death through asphyxia or sheer exhaustion...
.
Most plants have both male and female sex organs, but half of the 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 of the Ribbonwood do not obtain any female sex organs, the species using the process of cross-pollination. Attracted by the colour and smell of the flower, tiny beetle
Beetle
Coleoptera is an order of insects commonly called beetles. The word "coleoptera" is from the Greek , koleos, "sheath"; and , pteron, "wing", thus "sheathed wing". Coleoptera contains more species than any other order, constituting almost 25% of all known life-forms...
s and thrips crawl in and lay their eggs within the center of the flower, which contains the flower's pollen
Pollen
Pollen is a fine to coarse powder containing the microgametophytes of seed plants, which produce the male gametes . Pollen grains have a hard coat that protects the sperm cells during the process of their movement from the stamens to the pistil of flowering plants or from the male cone to the...
. Within the flower some of the sticky pollen gets trapped on the insect's bodies, and if the next flower they visit is a receptive one, it will pollinate
Pollination
Pollination is the process by which pollen is transferred in plants, thereby enabling fertilisation and sexual reproduction. Pollen grains transport the male gametes to where the female gamete are contained within the carpel; in gymnosperms the pollen is directly applied to the ovule itself...
and produce the seeds.
While other modern flowering plants produce seeds which have one cotyledon
Cotyledon
A cotyledon , is a significant part of the embryo within the seed of a plant. Upon germination, the cotyledon may become the embryonic first leaves of a seedling. The number of cotyledons present is one characteristic used by botanists to classify the flowering plants...
(monocotyledon
Monocotyledon
Monocotyledons, also known as monocots, are one of two major groups of flowering plants that are traditionally recognized, the other being dicotyledons, or dicots. Monocot seedlings typically have one cotyledon , in contrast to the two cotyledons typical of dicots...
s) or two (dicotyledon
Dicotyledon
The dicotyledons, also known as dicots, are a group of flowering plants whose seed typically has two embryonic leaves or cotyledons. There are around 199,350 species within this group...
s), the seedlings of the Ribbonwood have between three or four cotyledons. Also the Ribbonwood can produce more than one shoot per seed, while the seeds in all other plant species will develop and send up a single shoot.
The seeds are currently mainly spread through gravity dispersal, the seeds rolling down the steep mountain slopes to find their new home. The seeds are so toxic that most animals cannot eat them; however it is known that the native Musky Rat-kangaroo does disperse and bury some of these seeds. It has been suggested that the seeds were formerly dispersed by the now-extinct Diprotodon
Diprotodon
Diprotodon, meaning "two forward teeth", sometimes known as the Giant Wombat or the Rhinoceros Wombat, was the largest known marsupial that ever lived...
, on the basis that many Australian marsupials are adapted to cope with the toxins in Australian plants.
The plants have adapted a unique poison, a chemical called Idiospermuline contained within the seed, to prevent animals eating them. Researchers discovered the poison affects transmission of messages between individual nerve cells, which may cause seizures. In small doses this chemical can be used to save lives.
Discovery
First found by timber cutters south of Cairns in the late 19th century, then thought to be extinct. The Ribbonwood was then brought to the attention of the German botanist Ludwig DielsLudwig Diels
Dr. Friedrich Ludwig Emil Diels , 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 Pritzel through South Africa, Java, Australia and New Zealand. Shortly before the first world war he...
, who described the species in the genus Calycanthus
Calycanthus
Calycanthus is a genus of flowering plants in the family Calycanthaceae, endemic to North America. The genus includes two to four species depending on taxonomic interpretation; two are accepted by the Flora of North America....
as C. australiense in 1902, a remarkable disjunction for this otherwise North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
n genus. It was later believed to be extinct again, because when Diels finally returned to the location where this tree was found, the area had been cleared for a sugar cane farm.
The species was re-rediscovered in 1971, after the poison
Poison
In the context of biology, poisons are substances that can cause disturbances to organisms, usually by chemical reaction or other activity on the molecular scale, when a sufficient quantity is absorbed by an organism....
ous seeds of the plant were found in the stomachs of dying cattle in the region. In 1972, the Australian botanist T. S. Blake reassigned it to the new family Idiospermaceae and the genus
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...
Idiospermum (idio-, "unusual", and spermum, "seed"). In its 2003 revision, the Angiosperm Phylogeny Group
Angiosperm Phylogeny Group
The Angiosperm Phylogeny Group, or APG, refers to an informal international group of systematic botanists who came together to try to establish a consensus on the taxonomy of flowering plants that would reflect new knowledge about plant relationships discovered through phylogenetic studies., three...
retained it in the new genus, but restored the species to the family Calycanthaceae
Calycanthaceae
The Calycanthaceae is a small family of flowering plants included in the order Laurales. The family contains four genera and only 6-11 species, restricted to warm temperate and tropical regions:...
.
External links
- The families of flowering plants: Descriptions, illustrations, identification, information retrieval by L. Watson and M. J. Dallwitz
- The story of the rediscovery of Idiospermum by Prue Hewett
- An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG II by the Angiosperm Phylogeny Group