Top: Stapelia pulvinata, with a hatched maggot on the flower
Below: Bulbophyllum macrobulbon

Foul smell

I suspected some strange kind of dung, but when I asked one of the caretakers, he pointed me to the flower of Aristolochia gigantea. I had never expected these flowers smell so foul. We use to link the image of flowers to nice smells. The sparkling colours attract the occasional passerby to dip his nose in the flower. Which goes well most of the time, but sometimes the one smelling is in for a surprise. The flower emits something that is all but a lovely smell. This does not occur often, as smelly flowers, most of the time has a more or less smelly appearance. However, there are some very nice looking flowers with bad odours. The yellow-flowered climber Hibbertia scandens for instance has attractive flowers that smell like an old drawer in an arthropods-collection: a mixture of dead mice and mothballs. Most of the smelling flowers however have a colour and pattern that fits well with the smell.


Function

The smell of rotting meat has a function. The imitation is so good that it attracts many carrion-loving insects. A well smelling carrion flower attracts a cloud of green and blue bottle flies and such. They have to take care of the pollination. However, they will not always do so out of free will. Therefore, some of these flowers have been building into very clever flytraps, from which they can escape only after they have done their job. Other flowers are convincing enough that flies will eat from them or try to lay eggs on the surface.

The real carrion flowers are Stapelia species, succulent plants from the dryer regions of tropical Africa and India.  They are well-loved greenhouse plants, provided they do not flower. The starfish like flowers look more interesting then beautiful and do smell. Moreover, it works, as often enough flies do lay their eggs on Stapelia flowers. The hatching maggots will wrinkle about for a while, but besides some deceased litter mates, noting edible is around.
Stapelia and related genera like Hoodia and Heurnia are often specialized on a few species of carrion flies, at least in theory. The special types of flies do fly around even in Europe, as outside the flowers get fertilization often enough.
Stapelia wants a lot of light, full sun even, when not close behind glass and a dry cool (but always over 10°C) winter rest. Other smelly families are the Aristolochiaceae, already mentioned and the Araceae. The most convincing fly attractors belong to these two families.
In the orchid family too, many flowers looks and smells quite convincingly as dead meat. Chaubardiella tirina is a flower that looks very much as a piece of meat, leftover from a jaguar’s meal. The short, almost subterranean stem on which the flower rests strengthens that image.


Real smellers

Real smellers are amongst the Bulbophyllum-genus.  One of them is described as giving the smell of a heard of dead elephants (Bulbophyllum becarrii). Others have a two trap-fly attractor: To get the flies’ attention on a longer distance they smell after rotting meat, but when the fly comes close, their flowers look very much like flies. Those should induce the attracted flies to mate with them, thus taking care for fertilization much like flowers of Orchis or Telipogon. These flowers are not meat like coloured, but a fly like dark purple.

All these reddish brown and otherwise meat coloured flowers give you a warning. Know what you bring in your home. The long expected flower might be very beautiful, but very hard to stand close to.