Eriocaulon scariosum, commonly named common, rough or pale pipewort, is a species of tufted grass-like herbaceous plants, constituting part of the plant family Eriocaulaceae. The scientific name of Eriocaulon is derived from Ancient Greek εριον, erion, which means 'wool', and καυλός, caulos, which means 'stalk'. Common pipewort plants grow naturally in wetlands, bogs and drainage areas, from central and eastern Victoria, through eastern New South Wales, including the Australian Capital Territory, to eastern and north Queensland, Australia.
This species has obtained listing as "rare in Victoria" in the Victorian Department of Sustainability and Environment's current Advisory List of Rare or Threatened Plants in Victoria – 2005.
Based on specimen information "communicated from New South Wales in 1792, by John White, M. D.", this species was formally described using this name and in 1819 that was published scientifically by James E. Smith, London, in The Cyclopaedia.
Description
Eriocaulon scariosum is a native aquatic plant and is a monocot in the Eriocaulaceae plant family.
Eriocaulon scariosum is found across Victoria, New South Wales, Queensland and the Northern Territory. It is a small plant with small, thin and flat leaves and a thin, long stem. The plant has terminal buds, tiny flowers that bunched are together in a ball-like shape and at the flower base, there are fringed bracts.
During the flowering period from January to June (NSW), the leaves of Eriocaulon scariosum can range from 15 to 80 mm long and 1.5–2 mm wide and the bracts have an inner surface glabrous that are concave and scarious. The outer surface glabrous; have inner bracts obovate to spathulate, greyish and concave. The outer surface of the plant has short white hairs on the distal abaxial surface.
The flower heads of the plant species are 3–6 mm long, 3.5–5.5 mm wide. Eriocaulon produces new leaves outwards from the central crown. The involucral bracts are straw-yellow and are an egg-shaped leaf and come in elliptic to broadly elliptic forms. The involucral bracts are 1.75–2 mm long and 0.9–1.5 mm wide, they are obtuse and at maturity they are reflexed. Floral bracts have either a translucent to black appearance of a translucent base, they are 1.5–2.5 mm long, 0.6–1.1 mm wide. At the apex of the plant, there are white hairs that are thinly distributed.
There is a mixture of male and female flowers of Eriocaulon scariosum in the environment, or it will be either predominantly male or predominantly female. Male flowers stipitate with 3 outer tepals and one tepal linear. Female flowers are with 2 or 3 irregular outer tepals, one tepal absent or linear, others oblong-spathulate, dark brown to black; inner tepals 3, narrow-oblong to spathulate, white and short hair on the surfaces.
The key features of Eriocaulon scariosum that are stated and used by biologists in order to differentiate this species of Eriocaulon from other species in Australia are that its Epidermal cells of seeds have nearly equal diameters. The Epidermal cells of the seed are approximately isodiametric. The seeds of Eriocaulon scariosum are 0.4–0.53 mm long and 0.3–0.38 mm wide and it has projections that resemble a peg on longitudinal and transverse walls. Key features of the plant species is that the flowerheads of the Eriocaulon scariosum plant species has an outline that is level and smooth. It has involucral bracts situated below or close to the flowers; male sepals are formed into a spathe which are terminal; whilst female sepals are dimorphic with two different forms of laterals.
Habitat and distribution
The Eriocaulon sacriosum species is part of the Eriocaulaceae family of 13 genera and 1200 species. Within Australia, only the genus is found with 35 different species. Worldwide, the genus of Eriocaulon holds 400 different species, most are constricted within subtropical and tropical regions.
Eriocaulon scariosum’s establishment is native to Australia and its occurrence is rare in Victoria as stated in The Royal Botanic Gardens Victoria. The Eriocaulon scariosum plant species is categorised as “rare” in Victoria's in the Advisory list of rare or threatened plants in Victoria – 2014 maintained by the Victoria Department of Environment and Primary Industries (DEPI). This Advisory List is constructed from technical and scientific information and knowledge from a variety of botanic experts.