Stylidium is a genus of dicotyledonous plants that belong to the family Stylidiaceae. The genus name Stylidium is derived from the Greek στύλος or stylos, which refers to the distinctive reproductive structure that its flowers possess. 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 only found in Australia, making it the fifth largest genus in that country. Triggerplants are considered to be protocarnivorous or carnivorous because the glandular trichomes that cover the scape and flower can trap, kill, and digest small insects with protease enzymes produced by the plant. Recent research has raised questions as to the status of protocarnivory within Stylidium.
Stylidium scandens is a dicotyledonous plant that belongs to the genus Stylidium. S. scandens is endemic to Australia and is found primarily in the southwestern region of Western Australia. This species, along with Stylidium nymphaeum, has a unique characteristic among triggerplants in that its leaves, five centimetres long, end in a recurved barb that can grab hold of other vegetation and scramble or climb up to 30–60 cm in height over other plants, which is how it obtained its common name. Its flowers are bright pink and about 15 mm wide.
Stylidium violaceum, the violet triggerplant, is a dicotyledonous plant that belongs to the genus Stylidium. S. violaceum is endemic to Australia and is found primarily in the southwestern region of Western Australia. It can grow up to 50 cm including the scape. The mostly purple flowers are 10 mm tall and 6 mm broad. Leaves are 5 cm long and about 4 mm broad. Flowering occurs mainly from October to January. S. violaceum is found in locations with sandy or loamy sand soil texture conditions on hillslopes, dunes, or winter wet depressions and swamps.
Stylidium laricifolium, commonly known as giant trigger-plant, larch-leaf or tree triggerplant, or is a species of flowering plant in the family Stylidiaceae and is endemic to eastern Australia. It is a perennial subshrub with many linear leaves crowded along its few stems, the flowers white to pale pink and arranged in a single main panicle and smaller racemes.
Stylidium adnatum is a dicotyledonous plant that belongs to the genus Stylidium. S. adnatum is endemic to Australia and is found primarily in the southwest region of Western Australia.
Stylidium repens, the matted triggerplant, is a dicotyledonous plant that belongs to the genus Stylidium. S. repens is endemic to Australia and is found primarily in southwest Western Australia. This species is a creeping or scrambling triggerplant, which can spread over large areas as a tangled mat of stems and aerial roots. The older stems are grey whereas younger stems appear red and have terminal rosettes of small leaves, five mm to one cm in length. When the rains come, new roots and a one to three flowers emerge from the terminal rosettes. This is the only species of triggerplant known to regularly flower twice a year—in autumn and late spring. Pollination, which is typically very specialized in this genus, is achieved with a variety of insects in this species.
Stylidium turbinatum is a dicotyledonous plant that belongs to the genus Stylidium. S. turbinatum is endemic to Australia and is found in the northern part of Western Australia in the Kimberley region and near Darwin in the Northern Territory. This species is an erect annual herb that stands 6–15 cm tall. A 2–5 cm long stem bearing scattered leaves terminate in a tuft of 1–2 cm long upper leaves. Several scapes appear from these terminal tufts. The inflorescence is a raceme, which produces pink flowers whose petals are vertically paired. The hypanthium of this species is turbinate and is one of the distinguishing characteristics used to identify it. The sepals form ribs around the hypanthium, giving it a turbine-like appearance. Seeds of S. turbinatum are pale orange and around 0.2 mm long.
Stylidium graminifolium, the grass triggerplant, is a dicotyledonous plant that belongs to the genus Stylidium. This species used to belong to the Stylidium graminifolium complex, but the name was conserved for this single species when two others were split from the complex and introduced as new species in 2001. S. graminifolium is endemic to Australia and is one of the Stylidium species with the widest distribution throughout Australia. It is a perennial plant with grass-like leaves and is easily cultivated. It has been considered to be a carnivorous or protocarnivorous plant because it possesses glandular trichomes underneath the flowers that can trap and digest prey.
Stylidium tenerum, the swamp triggerplant, is a dicotyledonous plant that belongs to the genus Stylidium that was described by Curt Polycarp Joachim Sprengel in 1826. Robert Brown had described this species in 1810 under the name S. tenellum, a name which had already been used for another species in 1805 by Olof Swartz. To add to the confusion, Rica Erickson had described and illustrated this taxon in 1958 under the name S. uliginosum, another currently accepted name for a related species.
Stylidium aceratum is a dicotyledonous plant that belongs to the genus Stylidium. It occurs within the south west region of Western Australia
Stylidium calcaratum, the book triggerplant, is a dicotyledonous plant that belongs to the genus Stylidium. It is an ephemeral annual that grows from 5 to 10 cm tall but can grow larger at 20–30 cm tall in damp forest or scrub habitat. The few ovate leaves produced by this plant form basal rosettes around the stem. The leaves are around 3–5 mm long on short petioles. The scapes are 2–30 cm tall and produce single flowers in smaller plants and up to nine flowers in larger, more robust plants. Flowers are pink or white with red spots or lines at the individual petal bases. The petals are vertically paired and will fold over to meet each other at night or in adverse weather conditions. S. calcaratum is endemic to Australia and has a distribution that ranges from Victoria through South Australia and into Western Australia. Its habitat is recorded as being wet flats or near creeks and seepages. Pollination is achieved by a grey fly, Comptosia cuneata.
Stylidium ceratophorum is a dicotyledonous plant that belongs to the genus Stylidium. It is an annual plant that is endemic to the Kimberley region of Western Australia and northern parts of the Northern Territory. It attains a height of 12–30 cm with a basal rosette of small leaves. The leaves are petiolate, obovate, or lanceolate and are only 0.2–1 cm long. Solitary scapes are produced that bear golden yellow or orange flowers, 7–9 mm across. Its habitat has been reported as being sandy soils on creek margins in the presence of Stylidium rubriscapum and Stylidium diceratum or in river paperbark stands. S. ceratophorum appears similar to S. diceratum and may be confused with the species since they both have orange flowers. S. ceratophorum's corolla is twice as large as S. diceratum, though, as well as the deeply divided posterior corolla lobes of S. ceratophorum.
Stylidium edentatum is a dicotyledonous plant that belongs to the genus Stylidium. It is an annual plant that grows around 6 cm tall. The elliptical leaves form a basal rosettes around the stem. The leaves are around 0.3-0.8 mm long with recurved margins. Inflorescences are produced on solitary scapes and bear flowers that are white with rose-coloured markings at the base of the corolla lobes and two tooth-shaped throat appendages present. S. edentatum was a previously overlooked species that is related to and appears similar to S. calcaratum and S. ecorne. Allen Lowrie and Sherwin Carlquist described this species in 1989 and argued that if S. ecorne is considered distinct from S. calcaratum, then certainly S. edentatum warrants placement at the species level. It differs from S. calcaratum and S. ecorne by the long petioles on its recurved leaves, and the cuneate, obtuse, and unlobed posterior corolla lobes. They also have a distinctive lateral toothlike appendage at the base of each posterior corolla lobe. S. edentatum is endemic to southwestern Western Australia.
Stylidium perpusillum, the tiny triggerplant, is a dicotyledonous plant that belongs to the genus Stylidium, that occurs in south west Western Australia.
Stylidium weeliwolli is a dicotyledonous plant that belongs to the genus Stylidium. It occurs in the North West of Western Australia
Stylidium inaequipetalum, the Ayers Rock triggerplant, is a small herbaceous perennial plant in the genus Stylidium. It grows from 7 to 40 cm tall. Oblanceolate leaves, about 20-100 per plant, form a basal rosette with stems absent. The leaves are generally 15–81 mm long and 2–8 mm wide. This species produces 1-11 scapes per plant. Inflorescences are 7–40 cm long and produce pink flowers with petals all free and blooms almost year-round in their native range. S. inaequipetalum is endemic to the southwestern Northern Territory and Western Australia. Its typical habitat has been reported as sandy soils on sheltered creekbanks or in between rocks. S. inaequipetalum is most closely related to S. floribundum, though it is also closely allied with S. debile.
Stylidium preissii, the lizard triggerplant, is a species that belongs to the genus Stylidium. It is an herbaceous perennial that grows from 5–18 cm tall and has divided stems covered with tile-like leaves that are arranged in a spiral formation around the stem. The broadly trullate leaves are basifixed and held closely against the stems. The leaves are around 1.9 mm long and 1.0 mm wide. Inflorescences are umbellate racemes and produce flowers that are white, pale pink, or dark pink and bloom from November to December in their native range. S. preissii is only known from south-western Western Australia from Bremer Bay to Israelite Bay with a few populations near Jandakot. Its habitat is recorded as being white sandy soils in open heathland. S. preissii is distinct within its subgenus because it possesses a strap-like gynostemium column with a dilated cunabulum.
Stylidium perplexum is a species of triggerplant that is endemic to south-west Western Australia. It is a tuberous species that has many stems and has been described as "somewhat shrubby" at 15–40 cm tall. The linear leaves can be 2 cm long and are arranged around the stem in a rosette at the stem apices. The 8–19 cm tall scapes bear 6 to 14 flowers that are white with purple accents and corolla lobes that are laterally paired and 4–6 mm long.
Stylidium soboliferum, commonly known as Grampians triggerplant or bristly triggerplant, is a species of flowering plant in the genus Stylidium. It is endemic to the Grampians region in Victoria, Australia. The leaves are about 1–2 centimetres (0.39–0.79 in) long and are arranged in a small rosette. The flowers, which appear on 5–15 centimetres (2.0–5.9 in) long stems, have white to pale pink petals with a darker colour on the reverse side. Plants occur along drainage lines and in moist areas amongst rocks.
