Name:
Bonnet Orchid

Botanical name:
Cryptostylis erecta

Description:

SEX!!!

Now that grabbed your attention, but it’s relevant. Aesthetics aside, flowers are inherently all about sex. Sexual encounters in plants essentially involve the transfer of pollen from one to another. However, the Bonnet Orchid belongs to a group which takes sex to a new level.

Whilst some plants may rely on wind or other non-living agents as pollinators, others use various animals. To attract an animal to a flower you have to offer some kind of reward for effort, such as nectar. Sometimes, the offer is false, and Bonnet Orchids and their Australian relatives in the genus Cryptostylis have mastered such false advertising. They are pollinated by a male Ichneumon wasp (Lissopimpla excelsa), and what they advertise is sex. 

Male wasps are duped into thinking that the flowers are actually females because the flowers mimic pheromones produced by the female wasp. They then attempt to mate with the flowers, and in doing so pollen attaches to their bodies. As they move on to the next flower they transfer pollen to it; this is referred to as pollination by pseudocopulation. Presumably from the male wasp’s point of view it’s a real enough experience to keep him coming back for more. Somewhat surprisingly, all Australian Cryptostylis species are pollinated by the same wasp species.

There are 20 Cryptostylis species distributed from Malaysia through to New Caledonia and other Pacific islands. There are 15 species in Australia, occurring in all states except the Northern Territory. They belong to the family ORCHDACEAE (orchids); one of the largest plant families in the world. There are around 25 000 species found world wide, and approximately 700 in Australia.

Bonnet Orchids are ground orchids, unlike other orchids which may grow attached to rocks or trees. Unlike many other ground orchids in temperate Australia, Bonnet Orchids, along with most other Cryptostylis species, remain evergreen throughout the year and do not die down to an underground tuber. The single leaf is held above the ground on a short stalk. In colour and shape the leaf may resemble some eucalypt leaves on the upper surface but the lower surface is often purplish.

The flowering stems arise in summer through to early autumn. In common with almost all orchids there is a modified petal called the labellum or lip. In this case this is the most distinctive feature of the flower. It is lined with reddish-purple lines and markings and it is hooded, similar in shape to an old-fashioned bonnet, hence the common name. 

Where can they be seen in the Parklands:
Bonnet Orchids grow in sandy woodlands and forests throughout the NSW coast and adjacent areas, also into the Blue Mountains, and further afield in Victoria. I have only ever seen one small colony in the park; in the Lachlan Swamp paperbark forest, off the track as you walk in from the Duck Pond end. Here it grows on very slightly higher ground in between clumps of swordgrasses (Gahnia sp.).

Author:
Frank Hemmings