Stylidium alsinoides is a dicotyledonous plant that belongs to the genus Stylidium. It is an erect annual plant that grows from 18 to 30 cm tall. Obovate or elliptical leaves, about 20–100 per plant, are scattered along the elongate, glabrous stems. The leaves are generally 5.5–14 mm (0.22–0.55 in) long and 3–8 mm (0.12–0.31 in) wide. The bracts on the inflorescence can be as large as leaves and may be hard to distinguish them except for their growth habit: the leaves are alternate whereas the bracts are opposite.
Stylidium section Alsinoida is a taxonomic rank under Stylidium subgenus Andersonia. In his 1908 monograph on the family Stylidiaceae, Johannes Mildbraed had established the subgenus Alsinoides for species related to S. alsinoides, which were morphologically similar to species of subgenus Andersonia. In 2000, A.R. Bean published a taxonomic revision of subgenus Andersonia and reduced subgenus Alsinoides to sectional rank, renamed Alsinoida.
Stylidium section Andersonia is a taxonomic rank under Stylidium subgenus Andersonia. In 2000, A.R. Bean published a taxonomic revision of subgenus Andersonia and placed species within sections in the subgenus Andersonia, thus creating this autonym section. It contains 13 species. It is distinguished from the other sections in the subgenus by the inflorescences arising from leafless scapes, emerging from a basal or cauline cluster of broad leaves. The species in this section represent distributions from Southeast Asia, Malesia, tropical Australia, southern Queensland, and northern New South Wales.
Stylidium section Biloba is a taxonomic rank under Stylidium subgenus Andersonia. All the species in this section occur in northern Australia. In 2000, A.R. Bean published a taxonomic revision of subgenus Andersonia and established this section to separate these three species based on morphological and cladistic analysis. Species in this section form a basal rosette or cauline leaves and cymose inflorescences. The column is glabrous and dilated at the distal end.
Stylidium section Tenella is a taxonomic rank in the plant kingdom under Stylidium subgenus Andersonia. In 2000, A.R. Bean published a taxonomic revision of subgenus Andersonia and established this section to separate these eleven species based on morphological and cladistic analysis. This taxonomic rank is named after George Bentham's series Tenellae, which he established in his 1869 treatment of the family Stylidiaceae. Series Tenellae was not used in Johannes Mildbraed's 1908 taxonomic monograph in which he completely revised the subgeneric taxonomy of the genus. Mildbraed's treatment of the genus taxonomy is the general demarcation which has been used in subsequent revisions and additions.
Stylidium section Uniflora is a taxonomic rank under Stylidium subgenus Andersonia. In 2000, A.R. Bean published a taxonomic revision of subgenus Andersonia and established this section to separate these five species based on morphological and cladistic analysis.
Stylidium fluminense is a dicotyledonous plant that belongs to the genus Stylidium. It is an erect annual plant that grows from 15 to 30 cm tall. Elliptical leaves, about 10-40 per plant, are scattered along the stems. The leaves are generally 5–19 mm long and 1.5–6 mm wide. This species lacks a scape but has cymose inflorescences that are 5–11 cm long. Flowers are pink, mauve, or red. S. fluminense is found in northwestern Australia, including confirmed locations in the Hamersley Ranges and the Harding River near Karratha. Its typical habitat is sheltered sites with persistent moisture in sandstone gorges. It flowers in the southern hemisphere from June to October. S. fluminense is most closely related to S. alsinoides. Its conservation status has been assessed as data deficient.
Stylidium tenerrimum is a dicotyledonous plant that belongs to the genus Stylidium. It is an erect annual plant that grows from 4 to 30 cm tall. Linear, oblanceolate, or deltate leaves, about 5-24 per plant, are scattered along the stems. The leaves are generally 1.2-4.8 mm long and 0.3-0.8 mm wide. This species lacks a scape but has cymose inflorescences that are 4–11 cm long. Flowers are white and red. S. tenerrimum is found around Darwin in the Northern Territory of Australia and the Victoria River, though it hasn't been recollected there since the type location was chosen. Its typical habitat is sandy soils that remain moist, associated with grasses and sedges. It flowers in the southern hemisphere from April to August. S. tenerrimum is most closely related to S. alsinoides, though it differs by its asymmetrical petals. In his revision of the subgenus Andersonia in 2000, A.R. Bean placed S. evolutum into synonymy and noted that the type specimen of S. mitrasacmoides was not located and thus the application of this synonym is not certain. Tony Bean assessed this species' conservation status as data deficient in 2000.
Stylidium divergens is a dicotyledonous plant that belongs to the genus Stylidium that was described as a new species in 2000. The specific epithet divergens means diverging or separating, referring to the widely spreading posterior petals. It is an erect annual plant that grows from 7 to 27 cm tall. Obovate, orbicular, or elliptical leaves, about 2-6 per plant, form a basal rosette. The leaves are generally 4–21 mm long and 3–5 mm wide. This species generally has one to six scapes and cymose inflorescences that are 4–24 cm long. Flowers are white or mauve. S. divergens is endemic to Kakadu National Park in the Northern Territory of Australia. Its typical habitats are sandstone slopes and gullies. It flowers in the southern hemisphere in April. S. divergens is most closely related to S. accedens. Its conservation status has been assessed as data deficient.
Stylidium muscicola is a dicotyledonous plant that belongs to the genus Stylidium that was described by Ferdinand von Mueller in 1859. It is an erect annual plant that grows from 5 to 33 cm tall. Obovate or orbicular leaves, about 4-20 per plant, form terminal rosettes with some scattered along the stems. The leaves are generally 6–33 mm long and 5–28 mm wide. This species generally has one to eight scapes and cymose inflorescences that are 3–17 cm long. Flowers are white, pink, or mauve. S. muscicola's native range is concentrated in and around western Kimberley in Western Australia and extends to the northern parts of the Northern Territory and east almost to Queensland. Its typical habitat is a sheltered area along a sandstone ridge in sandy soils that remain moist in the dry seasons. It flowers in the southern hemisphere from February to September.
Stylidium schizanthum is a dicotyledonous plant that belongs to the genus Stylidium that was described by Ferdinand von Mueller in 1859. It is an erect annual plant that grows from 9 to 30 cm tall. Obovate, orbicular, or oblanceolate leaves, about 3-13 per plant, form basal rosettes. The leaves are generally 3.5–23 mm long and 1.5–12 mm wide. This species generally has one to four scapes and cymose inflorescences that are 9–30 cm long. Flowers are white, pink, mauve, or yellow. S. scizanthum's distribution ranges from the Kimberley region in Western Australia through the Northern Territory and into northern Queensland. It has been reported as far south as Mount Surprise and even in southern New Guinea. Its typical habitats are moist sand in Eucalyptus or Melaleuca communities, near creekbanks, or associated with sandstone landscapes. It flowers in the southern hemisphere from February to October. S. schizanthum is closely related to both S. pachyrrhizum and S. lobuliflorum.
Stylidium aquaticum is a dicotyledonous plant that belongs to the genus Stylidium. The specific epithet aquaticum refers to this species' typical habitat. It is an annual plant that grows from 18 to 30 cm tall. Linear leaves, about 20-100 per plant, are scattered along the elongate, glabrous stem. The leaves are generally 1.7–11 mm long and 0.1-0.3 mm wide. Petioles and scapes are absent. Inflorescences are 3–8 cm long. Flowers are pink or white. S. aquaticum is only known from its type location in northwestern Northern Territory of Australia. Its habitat is recorded as being a Melaleuca viridiflora swamp, growing in shallow water at a depth of around 7 cm. It flowers in the southern hemisphere in May. S. aquaticum is most closely related to S. fissilobum but differs mostly in the leaf shape. Its conservation status has been assessed as data deficient.
Stylidium capillare is a dicotyledonous plant that belongs to the genus Stylidium. It is an annual plant that grows from 6 to 13 cm tall. Obovate or orbicular leaves, about 4-7 per plant, form basal rosettes around the compressed stems. The leaves are generally 1.5–5 mm long and 1–3 mm wide. Petioles are absent. This species usually has one to two scapes per plant and 6–13 cm long inflorescences. Flowers are white and bloom from March to June in the southern hemisphere. S. capillare's distribution ranges from Litchfield National Park in the Northern Territory east to Cooktown Mareeba in northern Queensland, Australia. Its habitat is recorded as being sandy soils in eucalypt woodlands and swampy Melaleuca species communities. S. capillare is most closely related to S. nominatum. Its conservation status has been assessed as secure.
Stylidium fissilobum is a dicotyledonous plant that belongs to the genus Stylidium. It is an annual plant that grows from 5 to 50 cm tall. Linear or deltate leaves, about 4-34 per plant, are scattered along the elongate, glabrous stem. The leaves are generally 1–6 mm long and 0.3-0.7 mm wide. Petioles and scapes are absent. Inflorescences are 3–18 cm long. Flowers are pink, white, or mauve and bloom from March to July in the southern hemisphere. S. fissilobum's wide distribution ranges across northern Australia from the western Kimberley region and Northern Territory eastward as far as Mount Surprise in Queensland. Its habitat is recorded as being wet sands at swamp edges in association with grasslands and sedgelands. Due to its weak stem, this species often threads its way through supporting branches and leaves of the dense grass and sedge cover. S. fissilobum is most closely related to S. aquaticum and S. oviflorum. Its conservation status has been assessed as data deficient.
Stylidium nominatum is a dicotyledonous plant that belongs to the genus Stylidium. It is an annual plant that grows from 4 to 15 cm tall. The oblanceolate leaves, about 5-15 per plant, form basal rosettes around the stem and are 2.5–9 mm long, 0.5-1.5 mm wide. About 4-11 leaves per plant are also scattered along the stem and are generally 2.3-4.7 mm long and 0.3-0.5 mm wide. Scapes are absent. Inflorescences are 2–6 cm long and produce white flowers that bloom from April to June in the southern hemisphere. S. nominatum is endemic to the northern area of Kakadu National Park and Melville Island in the Northern Territory. Its habitat is recorded as being sandy soils in Melaleuca viridiflora woodlands, bases of sandstone escarpments, and gravelly yellow soil in flat, treeless areas. S. nominatum is most closely related to S. capillare. In his recent revision of the subgenus Andersonia, Anthony Bean (A.R.Bean) noted that there is a large variation recorded in the specimens of this species and more work would need to be done to determine if there's more than one taxon involved with this species. Further evaluation may reveal additional species.
Stylidium ericksoniae is a dicotyledonous plant that belongs to the genus Stylidium. It is an annual plant that grows from 6 to 15 cm tall. The linear or deltate leaves, about 20-100 per plant, are mostly in terminal rosettes but with some scattered along the elongate stem. The leaves are generally 4.0–9.5 mm (0.16–0.37 in) long and 0.6–1.1 mm (0.024–0.043 in) wide. Petioles are absent. This species produces 1–20 scapes per plant. Inflorescences are 5–11 cm (2.0–4.3 in) long and produces a single pink or mauve flower that blooms from March to August in the southern hemisphere. S. ericksoniae is endemic to the northern areas of the Northern Territory of Australia. Its habitat is recorded as being damp sand near sandstone rocks or on swampy drainage channels. It's been found in association with Micraira and Pandanus species. S. ericksoniae is most closely associated with S. pedunculatum. Its conservation status has been assessed as data deficient.
Stylidium trichopodum is a dicotyledonous plant that belongs to the genus Stylidium. It is an annual plant that grows from 6 to 20 cm tall. The linear leaves, about 20-200 per plant, are scattered along the elongate, glabrous stems. The leaves are generally 3–9 mm long and 0.2-0.7 mm wide. Petioles are absent. This species produces 1-10 scapes per plant. Inflorescences are 2.6–6 cm long and produce a single yellow or orange flower that blooms in June and July in the southern hemisphere. S. trichopodum is endemic to northern Queensland and is only known from a few populations. Its habitat is recorded as being moist sandy soils on flat or gently sloping terrain, sometimes in areas dominated by Melaleuca species. S. trichopodum is most closely related to S. pedunculatum, though it differs by its much larger flower and its cauline leaves instead of terminal rosettes for S. pedunculatum.
Stylidium section Debilia is a taxonomic rank under Stylidium subgenus Tolypangium. In his 1908 monograph on the family Stylidiaceae, Johannes Mildbraed had established this section as Debiles. In 1999, A.R. Bean published a taxonomic revision of several sections in subgenus Tolypangium in which he renamed the section from Debiles to Debilia.
Stylidium section Lanata is a taxonomic rank under Stylidium subgenus Tolypangium. It was described in 1999 by Anthony Bean. Two of the species in the section were also described by Bean in 1999, but S. eriorhizum was moved from section Debilia to section Lanata. The three species differ from those of section Debilia by their perennial habit, thickened woolly plant bases, indeterminate central rachis of the inflorescence, and larger, spherical seeds that possess a small nipple.
Stylidium darwinii is a small, erect annual plant that belongs to the genus Stylidium. It grows up to 4.5 cm (1.8 in) tall. Elliptic-oblong or obovate to orbicular leaves are scattered and alternate along the simple, glabrous stem. The leaves are generally 2–3 mm long and 1.5-1.8 mm wide. Inflorescences produce many violet-pink flowers, which flower from September to November. Stylidium darwinii is only known from Anshi National Park in the Uttara Kannada district of Karnataka, India. Its habitat is recorded as being moist gravelly soils on the outskirts of evergreen forests near roadsides at an altitude of 530 m (1,739 ft). It can be found in association with several carnivorous plant species, including Drosera burmannii, Drosera indica, and Utricularia caerulea. The specific epithet darwinii was given to this species in honor of Charles Darwin.
