Polygala linariifolia

Polygala linariifolia, commonly known as "Native Milkwort", is a herb that can be either annual or perennial, reaching an approximate height of 20 cm. Stems possess curled or straight hairs, tap roots are woody in nature, whilst branches are generally up right. Leaves typically grow up to 3.5 cm in length and are usually obovate in shape, getting broader towards the tip, however are known to vary in shape (linear-oblong or narrow-elliptic). Leaves are typically 5–45 mm in length, 1–10 mm wide, with a short point at the tip and dull in texture, due to the sparse covering in short hairs. Flowers are arranged in a lateral raceme extending 1–9 cm, on a pedicel 2–6 mm with individual flowers 3–5 mm in length. Flowers vary in colour between a bluish purple and yellow, however on occasion may be white. Flowering typically occurs between September–February depending on the season. The fruit capsule is flattened in a broad-oblong shape approximately 3–4 mm long with a narrow wing. Encompassed within the capsule are black seeds with white hairs. == Distribution ==

P. linariifolia is known to exist worldwide in countries such as China, Philippines, Thailand, India, New Guinea and Cambodia, in addition to Australia, which it is known to occur across four Australian states/territories, those including New South Wales (NSW), Queensland (QLD), Northern Territory (NT) and Western Australia (WA). In WA, a number of populations have been observed in the Northern Kimberley, in the Mitchell Plateau area, whilst in the NT, individuals have been recorded in the north of the territory, in areas including Adelaide River and Koolpinyah. However, due to nomenclature issues, it is likely that there are more populations present or that have been recorded under a different taxon name. == Taxonomy ==

P. linariifolia was first named and published by German botanist and plant taxonomist, Carl Ludwig Willdenow in 1807 in the publication 'Species Plantarum. Editio quarta 3'. P. linariifolia is placed within the Fabales order. Successionally, it is located within the Polygalaceae family, where the Polygalaceae has a presence of five genera and 86 species within Australia. Some members of the Polygalaceae family (families such as some Comesperma and Polygala) are known to emit distinctive odours from the roots. Previously, P. linariifolia has been misapplied to a number of more recent Polygala species including: P. bifoliata, P. dimorphotricha, P. galeocephala and P. saccopetal. In addition to being misapplied, a number of variations of the species exist in the form of spelling differences and synonyms. P. linariifolia may also be spelled P. linarifolia and can be referred to as P. chinensis var linarifolia and or P. triflora As a result, it makes it difficult to determine the true, worldwide abundance of P. linariifolia including across Australia, especially when P. linariifolia is currently referred to in NSW biodiversity and conservation legislation. == Habitat and ecology ==

P. linariifolia commonly establish in sandy soils, typically in dry eucalypt forests with sparse understoreys, however are also known to grow in dark sandy loams on granite and within yellow podsolic soil on granite which are associated with layered open forests and shrubby forests of dominant Callitris and Eucalyptus species. Within the Australian continent, a number of tree species have been identified to associate with P. linariifolia such as Eucalyptus sphaerocarpa, Angophora floribunda, Allocasuarina torulosa, Eucalyptus trachyphloia, Angophora leiocarpa, Lophostemon suaveolens, Corymbia henryi in addition to the native herb, Wahlenbergia. Populations within New Guinea and the Philippines have been identified to show an erect habit, however when the main stem is subject to disturbance or destruction, a more prostrate habit is formed with the growth of lower, ground covering branches. The degree at which these individuals change between an erect habit and prostrate habit will alter depending on a range of factors eg. the severity of disturbance and destruction. == Conservation status ==

Within Australia, populations of P. linariifolia are known to vary in conservation status, commonly being placed in the categories of rare, sparse, occasional and common. Species listed as endangered are at very high risk of becoming extinct in Australia in the near future, however in the Australian Commonwealth legislation, the Environment Protection and Biodiversity Conservation Act 1999, P. linariifolia is not listed under any category. This is also the case for WA's, NT's and QLD's state/territory related threatened flora legislation. Key threats that may impact population abundance and distribution of P. linariifolia include, clearing of habitat, grazing from stock and feral animals, competition and shading from invasive flora, disturbance from infrastructure maintenance and construction, changes in fire frequency and severity, forestry activities that disturb soil structure and damage ground cover and uncertainty in taxonomic classifications amongst species, making management difficult. == References ==