On the nose
Not all flowers smell as sweet as a rose – some are decidedly stinky
Think of a summer evening, with a waft of frangipani or pittosporum flower in the air. Or reflect on when you last passed a blousy rose perched at nose level and were unable to resist taking a sniff. Plants are as much about scent as they are about colour and form, but there are times when they’re decidedly on the nose. Take the giant titan arum (Amorphophallus titanum) bloom and what I would describe as its ‘dead-possum’ aroma. Or Rafflesia arnoldii, another huge flower from the jungles of Indonesia and Malaysia, with a similarly unpleasant odour, all the better to attract flies and carrion beetles. Then there’s its close relative, Sapria himalayana, which has generally smaller but smellier flowers.
A less well-known stinker is Bulbophyllum fletcherianum. This orchid’s aroma is so strong and revolting that collectors have vomited in their attempts to bring the plant into cultivation. With leaves up to 2m long and nearly 50cm wide, and ‘pseudobulbs’ the size of grapefruit, it’s one of the largest orchids in the world. It grows in just a few ravines in southern New Guinea, mostly attached to trees and rocks. The collector of the first material distributed to botanic gardens in Australia was lowered by rope down a cliff face but could barely make it back after throwing up from the stench. Those at the top reacted similarly, and only after one of them snapped off the flowers and threw them into the ravine could they safely transport the plant back to Australia.
It takes humidity and temperatures over 30˚C to bring out the full odour, so plants flowering in Sydney and Melbourne have left some brave visitors disappointed. Unpleasant-smelling relatives include Bulbophyllum putidum and B. foetidum.
Whole genera can be tainted by their odours. The blooms of almost all Stapelia species are described as smelling like rotting flesh. And the genus Sterculia, which is named after the Roman god of manure, includes species where all parts of the plant emit foul or, at best, unpleasant scents.
Then there is the cabbage family, Brassicaceae. When I was a youngish child, we grew our first crop of broccoli at a holiday house just out of Castlemaine, in central Victoria. We left the harvesting a little late, and I was so taken by the yellow flowers the plants had produced that I cut off a few of the heads and put them in a vase. We returned a few weeks later to the stench of rotten cabbage wafting through the house.
All Brassicaceae will stink if you leave them in a confined space for too long, and that applies as much to the vegetative plant as it does to the flowers. The leaves of the aptly named New Zealand shrub stinkwood (Coprosma foetidissima) have that same rotten-cabbage-like smell.
some real stinkers
Some plants have quite evocative and specific odours. The needles of the North American white spruce, for instance, reputedly smell like cat urine. In a similar vein, the root of the beautiful Fritillaria imperialis has the unfortunate musky aroma of fox urine, which continues to linger long after the plant has been removed from a garden bed.
It’s not just the exotic plants, of course. Given the fresh tang of a lime or lemon, it may seem odd that Australian representatives of the citrus family, Rutaceae, have a stinky reputation. Examples include Zieria arborescens, which is also called stinkwood, and many of the Boronia species, some of which invite my ‘smells like dead possum’ descriptor.
In the emu-bush family, the smell of Myoporum floribundum
after rain resembles wet socks, according to some. The same is true of lantana, which, although not an Australian native, has become well established in many areas. Its floral scent is offensive to some, including, it seems, many in Malaysia, where it’s called bunga tahi ayam, the chicken poo flower.
A ripe fruit is usually an olfactory treat – think fresh peaches and mangoes – unless it’s the tropical durian, which emits a smell of decay to attract orangutans from many kilometres away. The fruit of noni (Morinda citrifolia) and Ginkgo biloba
also have acrid aromas, which are often described as similar to vomit. Again, opinions are divided. Despite Morinda citrifolia
sometimes being called ‘starvation fruit’, because it should only be eaten as a last resort, it is popular in Hawaii and elsewhere in the Pacific, albeit when mixed with other foods and taken largely for its reputed health benefits.
Then there are plants (or plant-like things) that smell and look unpleasant, from the dung-fragranced flowers of the parasitic and odd-looking desert plant Hydnora africana, which attracts dung beetles to pollinate the flowers, to the well-named genera of stinkhorn fungi, such as Phallus, Aseroë and Clathrus.
I haven’t even mentioned plants that my more polite botanist friends describe as smelling ‘manly’, such as the ornamental pear (Pyrus calleryana), sweet chestnut (Castanea sativa) and the male flowers of the carob tree.
All scents have their uses to the plant and, when emitted from a flower or fruit, usually attract an animal of some kind.
So, while certain odours may be odd or offensive to us, there is sure to be something out there that likes what it smells.