There are 3 species of Sowerbaea found in Western Australia (out of a total of 5 species) and one of these species is Sowerbaea laxiflora Lindl. It is a tufted perennial which grows down the west coast, and some inland areas, mainly from Geraldton south to Albany. It is known as Purple Tassels and is a tufted perennial herb 0.15-0.45 m high. It has purple flowers August to November.
Stylidium (also known as trigger plants) is a genus of dicotyledonous plants that belong to the family Stylidiaceae. Pollination is achieved through the use of the sensitive 'trigger' which comprises the male and female reproductive organs fused into a floral column that snaps forward quickly in response to touch, harmlessly covering the insect in pollen. Most of the approximately 300 species are found in Australia, making it the fifth largest genus in this country. Trigger plants are considered to be protocarnivorous or carnivorous because of the glandular trichomes that cover the scape and the flower can trap, kill and digest small insects with protease enzymes produced by the plant. If you wait a moment or two hopefully you will see the trigger working on this little yellow flower:
In Western Australia alone, there are now more than 150 species, at least 50 of which are in the area immediately around Perth. One of the larger species is Stylidium schoenoides or "Cow Kick" so named for the powerful 'kick' when triggered. The flowers of this species are only 5cm (2"). so most of the Stylidium flowers are very small.
I can remember, as a child. being really intrigued by these plants and loved to gently touch the flower to make the trigger work. It is many years now since I have seen one.
Senna cardiosperma is an inland species and common in the Kalgoorlie region of Western Australia. It also occurs around Esperance in the mallee, arcing 100km (over 60 miles) NW to the NE and becoming more common further north. It germinates readily in a variety of well-drained soils after bushfire or soil disturbance and can grow to around 2 metres (6') high, although most plants are usually shorter and quite bushy.
The flowers tend to be distinctly yellow when growing in sandy loam but develop an orange tinge when growing over gravel. It is a prolific producer of flowers and flowering times are usually between July and November.
You know of course why I chose the last one....yes, it's yellow!!