Not only do south-western Australian orchids have imaginative common names but their flowers are arguably some of the most stunning in this biodiversity hotspot. The flowers of the 320 or so species have a wide range of colours and shapes.
Many orchids don’t produce nectar to attract insects to spread their pollen, instead using deception to trick their pollinators. For example, some donkey orchids resemble nectar producing native pea flowers, thus tricking native bees into visiting their flowers (floral deception).
Even more intriguing are the orchids that use sexual deception to get pollinated. In the flying duck orchid (shown in the ‘other orchids’ gallery) the ‘duck’s beak’ of the flower not only looks like a female wasp but also emits similar pheromones thus attracting male wasps. When a male wasp lands on this part of the flower to try and mate with it the ‘beak’ flips it over and pollen is deposited on the wasp’s back.
Sexual deception has evolved a number of times in orchids – it occurs in at least 10 genera of Australian orchid. Hammer orchids, like the slender hammer in the ‘other orchids’ gallery, and some species of spider orchid, such as the zebra orchid, use this strategy. Sexual deception tends to be very specific with each orchid only attracting one insect species.
Spider orchids and their affiliates
Some of the largest South-west Australian orchids are those in the genus Caladenia, particularly the spider orchids. They also have more threatened species than any other Australian orchid genus.
Small-flowered caladenias and close relatives
Compared with their colourful cousins above, greenhoods orchid flowers are more subtle. New Zealand also has a large number of greenhood orchid species.
The orchids below contain two of the strangest flowers that I’ve ever seen – the slender hammer and flying duck (and yes, it does resemble a flying duck!).