Step into the rainforests of the Daintree lowlands at the moment and you’re likely to whiff the pervasive scent of the rare Javan Ash (Ryparosa javanica). The abundant flowering emits a sweet, slightly off-smell, like five-day-old socks or raw hamburger mince.
The Javan Ash is found in both Java and Australia. This forms evidence of the mixing of the continental biota of the Australian and Asian plates, which are believed to have collided about fifteen million years ago, in the vicinity of what is now the Timor region.
As a defence against herbivores, these plants emit the poisonous gas Hydrogen Cyanide (HCN), through a process called ‘cyanogenesis’.
HCN is poisonous, not only to animals that the eat plants, but to the plants themselves. To prevent poisoning themselves, the plants limit the production of HCN through the strategic storage of both cyanogenic glycosides and an enzyme in adjacent vacuoles of the cell. When the cell is damaged the compartment walls are breached and the reaction takes place. In this way, HCN is produced only when needed.