Charming!

Just because it's trigger season, and I live in Stylidium central, here's one of my favourites that is flowering now. The Lovely Trigger Plant, Stylidium amoenum (amoenus is Latin for charming or showy). In a genus of exquisite plants, you have to be special to earn a specific epithet like that.
(It appears to have been collected by Robert Brown, botanist on Mathew Flinders voyage. I think he had more than a passing acquaintance with curious and attractive flowers, but in those days Stylidium were classified as Lobeliaceae, though Brown had his doubts).

It is happily abundant in Jarrah forest over quite a large area of the S.W., but seems sadly to be a Phytophthora cinnamomi martyr. Grows up to half a metre tall, and flowers for a long period from late spring.

Itchy triggers

That bee-fly in the last post is quite a sizable animal. Big in fact. Probably about 20mm. This is one of the trigger plants that it would be fitted in size to pollinate, the Book Trigger Plant, Stylidium calcaratum.
This is an annual, up 20cm tall, with a long season from October to January. The common name refers to the fact that the flower closes like a book at night or in cold weather, obviously to save itself for when its specialist pollinators are out and about.
The flowers are white or shades of pink, and can be sprinkled as liberally as confetti around granite outcrops, edges of gravel roads and other water-gaining sites. The trigger is hinged so it strikes upwards, hitting the insect on the ventral rather than dorsal side. I wonder if that is more or less of a shock?

This is quite a widespread species, being found over most of the south west. It's also found in other states. WA has 70% of Stylidium taxa, so is a centre of Stylidium diversity, and the Busselton-Margaret River-Augusta region is particularly rich.

Rica Erickson's explanation of trigger plant action is still as good a way to read about them as ever.