Alternative names: Not Applicable

Description:
Annual or perennial herbs with alternate or opposite exstipulate leaves sometimes condensed into a basal rosette.

Inflorescence simple or compound, cymose, usually glandular-pubescent; flowers bisexual, zygomorphic or superficially actinomorphic; sepals 5, scarcely connate to unequally fused, persistent; petals 4 and 1 forming the labellum, fused into a short tube and often split next to the labellum, the lobes radiating out or paired either vertically or laterally; labellum smaller than the corolla lobes, irritable in Levenhookia; stamens fused around the style (column), irritable in Stylidium; stigma with 2 branches or 1 cushion or rarely protruding and strap-like structure, situated between the anthers; ovary inferior, with 2 carpels, 2- or 1-celled with many ovules on a central or basal placenta.

Fruit a septifragal capsule dehiscing mainly at the apex; seeds with endosperm.

Distribution:  5 genera and about 150 species mainly in Australia but also in tropical Asia, New Zealand and temperate South America.

Biology: The explosive pollination mechanism involving actively moving floral parts is triggered off by foraging visitors to the flowers and ensures greater cross pollination. It is often a highly specific relation with a specific kind of an insect thus ensuring that pollen of one flower is deposited on the same part of the pollinator as where the stigma of another flower will touch the visitor. In Stylidium (except in S. beaugleholei) the apex of the column is activated to touch the visitor, while in Levenhookia the visitor in a definite position triggers off the removal of the protective labellum from the stamens and stigma at the apex of the column (Erickson (1958) Triggerplants).

Key to Genera:

1. Column erect, not irritable and covered by a hooded irritable labellum; stigma 2-branched	LEVENHOOKIA 1.
1. Column recurved, irritable (not in S. beaugleholei); stigma cushion- or strap-like	STYLIDIUM 2.

Author: Prepared by H. R. Toelken