Stylidium calcaratum. Image taken from http://www.flickr.com/photos/myrmician/5557921811/
Today I have decided to write about an interesting little plant that is currently flowering here in the south west; the book trigger plant.
The book triggerplant belongs to the plant family Stylidiaceae and to the genus Stylidium. Stylidium, commonly called triggerplants, are native but not endemic to Australia. They are found across Australia in New South Wales, Queensland, the Northern Territory and Western Australia. Here in Western Australia there are about 206 species of triggerplant.
Stylidium are annual and perennial herbs with irregular flowers which have 4 distinct petals and one petal that is highly modified into a tiny recurved labellum. The throat of the labellum contains a column of combined stamens that are joined to the style. This highly modified petal is a specialised pollination tool and when triggered it is suddenly released to deposit or receive pollen from visiting insects.
The book triggerplant’s scientific name is Stylidium calcaratum. Stylidium calcaratum are short lived slender rosetted annual herbs which grow to about 2 to 20 cm in height. The leaves of Stylidium calcaratum can be ovate (oval shaped), obovate (egg shaped) or circular. Its flowers are white or pink often with red markings near the bases of the petals. The petals of the book triggerplant are paired vertically. The erect pair of petals are 3 toothed and are about 2 to 7 mm long. The extended pair of petals are curved and are about 4 to 10 mm long. The labellum of Stylidium calcaratum is concave.
The book triggerplant flowers between July and December, January. It can be found in a variety of habitats from Shark Bay to east of Esperance and is common throughout the south west. It is usually found in damper areas of forests, woodlands, heaths and granite outcrops and can cover large areas around ephemeral pools.
Stylidium calcaratum is very small and can be easily missed, so be sure to look and tread carefully when out walking, it’s a wonderful little plant to find.
Stylidium calcaratum. Image taken from http://florabase.dpaw.wa.gov.au/browse/profile/7696
Sources:
- Wheeler, J., Marchant, N. and Lewington, M. (2002). Flora of the South West of Western Australia, Volume 2. Australian Biological Resources Study and University of Western Australia Press. Perth, Western Australia.
- Florabase
