Idiospermum is a genus containing a single species of tree, Idiospermum australiense, found in Australian tropical rainforests. The species represents one of the earliest known lineages of flowering plants, dating back as far as 120 million years. It is found today only in the Daintree and Wet Tropics rainforests region of north-eastern Queensland. It is endemic to a very few locations in north-eastern Queensland (e.g. in Daintree National Park), in the very wet lowland parts of the forest, in groups of 10–100 trees together (rather than scattered individuals). Common names include ribbonwood and idiot fruit. Description Ribbonwood trees grow naturally in their wet tropical rainforest habitats as evergreens up to about tall and about in diameter at breast height (DBH). The simple leaves grow singly, in pairs or in whorls of 3–4, each one measuring about long and wide. The flowers measure in diameter, with all floral organs spirally arranged. The tepals are initially creamy white when the flower opens, then turn red as the flower ages. The "fruits" have very distinctive features and do not fit within the definition of true fruits as such: all the protective layers decay while still on the parent tree and each one released is an extremely large ( diameter) naked plant embryo. This is one of the largest embryos of any flowering plant. It is very toxic, inducing symptoms in cattle similar to those of strychnine poisoning. Reproductive organs Plants have both male and female sex organs, but half of the flowers of the ribbonwood do not produce any fertile female organs. Attracted by the scent and colour of the flower, small beetles and thrips are the main floral visitors. they 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 most modern flowering plants produce seeds which have one cotyledon (monocotyledons) or two (dicotyledons), the seedlings of the Ribbonwood have between two and five cotyledons. Also the ribbonwood can produce more than one shoot per seed (usually one per cotyledon). I. australiense is the only known species in which the flowers display a continuous spiral series of bracts, sepals, petals, stamens and finally staminodes. Seeds and their dispersal ecology The seeds are