Wildflowers of Western Australia

A triggerplant has a spring-loaded, touch-sensitive column hidden under the petals which flicks over when an insect lands on the flower for a feed of nectar.

At the end of this column are the male and female parts of the flower (anther and stigma).

This action either deposits or collects pollen, depending on the cycle of the plant.

The pollen-filled anthers (male) appear first on the young flower, then as it matures the sticky stigma (female) takes over and is ready to collect pollen. This cycle prevents self-pollination.

Most of the bees I have seen visiting these flowers have a worn spot on their back where they have been repeatedly whacked by the column.

More bee pics

The small lobes in the centre of this beautiful Queen Triggerplant prevent access to the nectar unless the insect lands on the lower petals.

The clever design of the flower forces the insect to land on the same position each time.

These plants are amazingly precise.

To avoid producing hybrids, different species of triggerplants have various shapes and lengths of the column, which can strike from under, over or even from the side.

Therefore, an insect visiting two species can be struck at different locations on the body.

These triggerplants strike the insect on the underside of the abdomen like "a punch in the guts".

So named because the flower closes like a book at night or in cold weather.

Mostf triggerplants have two pairs of petals.

Here you can see 2, 3, 5 and 6-petalled flowers, but they are very rare.

3 5 5 6

After the column has been triggered it gradually resets, usually within an hour, ready to assault another innocent insect looking for nectar or pollen.

Most of the world's 260+ known species of Stylidium occur only in the South-West of Western Australia, highlighting this area as the major centre of triggerplant evolution.

Stylidium is the fifth largest genus in Australia.

Click on this image to see the trigger action in more detail.

Stylidium is believed to be carnivorous (or protocarnivorous).

It has been reported that the numerous sticky glands on the flowering parts of triggerplants secrete enzymes to trap and digest tiny insects.

The largest of all triggerplants and named for the powerful 'kick' when triggered.

These are only 5 cm (2in) tip to tip, so most stylidium flowers are very small.

Small children are advised not to touch these flowers.

Kingdom: Plantae
Angiosperms
Eudicots
Asterids
Order: Asterales
Family: Stylidiaceae
Genus: Stylidium

The innocence of the flower belies the mamba-shaped head of the column, ready to strike and just as fast.

Click on the image to see this in detail.

Boomerang Triggerplant – Stylidium breviscapum

For more detailed information, check out the Wikipedia Triggerplant page.