Eriocaulon scariosum

Eriocaulon scariosum is a native aquatic plant and is a monocot in the Eriocaulaceae plant family.[7]

Eriocaulon scariosum is found across Victoria, New South Wales, Queensland and the Northern Territory.[8] It is a small plant with small, thin and flat leaves and a thin, long stem.[9] 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.[9]

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.[8] 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.[8]

The flower heads of the plant species are 3–6 mm long, 3.5–5.5 mm wide.[10] Eriocaulon produces new leaves outwards from the central crown.[11] The involucral bracts are straw-yellow and are an egg-shaped leaf and come in elliptic to broadly elliptic forms.[10] 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.[10] 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.[10] 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.[8] 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.[8]

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.[10] 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.[10] Key features of the plant species is that the flowerheads of the Eriocaulon scariosum plant species has an outline that is level and smooth.[10] 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.[10]

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.[12] Worldwide, the genus of Eriocaulon holds 400 different species, most are constricted within subtropical and tropical regions.[13]

Eriocaulon scariosum’s establishment is native to Australia and its occurrence is rare in Victoria as stated in The Royal Botanic Gardens Victoria.[14] 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).[15] This Advisory List is constructed from technical and scientific information and knowledge from a variety of botanic experts.

The conservation status of Eriocaulon scariosum is deemed as to not be under threat and widespread across Australia.[16] It is not classified in the Federal Environment Protection Biodiversity Conservation Act 1999 (EPBC Act).[7] The plant's distribution is commonly spread in eastern and central Victoria, New South Wales, Queensland and Northern Territory.[16] Eriocaulon scariosum grows in west areas such as wetlands, bogs, melaleuca swamps and lakes and springs, drainage areas and soils that contain sand. In the damp areas, Eriocaulon scariosum is often overlooked and inconspicuous as it is difficult to find due to its small size.[17]

The Castlereagh Swamp Woodland Community, an endangered ecological community, facilitates habitat for several plant species that are described as of regional importance, according to the Urban Bushland Biodiversity Survey, NPWS (1997). These include Eriocaulon scariosum.[18]

Eriocaulon Scariosum is a part of a related Queensland complex of Eriocaulon species, which includes Eriocaulon odontospermum and as well as Eriocaulon annum.[12] Eriocaulon scariosum is reported at three Fraser Coast localities, Tuan Forest, Talegalla Weir and Fraser Island.[7] It is recorded in the Wilde Bay district in the Queensland Herbarium Censis and is classified as Least Concern by the Queensland Nature Conservation Act.[7]

[14]

The flowering period of the Eriocaulon scariosum plant happens from the month of January through to June each year.[22]

The Eriocaulaceae family grows the best in the Western Hemisphere, more specifically the ‘New World tropics’. The centres of diversity of Eriocaulon include Africa, the Indian subcontinent and South America.[12]

The species in the genus is mainly made up of small perennial herbs and are situated in shallow water or damp habitats.[13] In Eriocaulon plants, the nectar glands on the apices of petals make fluid that acts on attracting insects, which leads to insect pollination.[19]

Within wet habitats, the Eriocaulon scariosum number in prevalence is determined by the occurrence of fire, water levels and other contesting plants such as grasses.[23] Experiments present that the plant is weak in survival in comparison to other wetland plant species.[23]

The Eriocaulon species has become a more recurrent plant because their threats and requirements to grow has been studied and more understood. In order for the plants to grow better and more easily, the substrate levels for the environment needs to be soft water with substantiating CO₂.[11] The species of plants respond firmly towards the root of fertilisation. They can do extremely better with higher CO₂ levels and light. Two signs that the plant is not growing well are if the plant has a weak root arrangement and older leaves growing old at a faster rate.[11]

If the plan has stiff instead of soft laves and the formations of the leaves are neat and not messy or indented, it means the plant is strong.[11]

As they grow bigger, many species of Eriocaulon can naturally produce baby plantlets, also known as side shoots.[11] Sometimes, the baby plantlets are created when the plant goes through a period of either instability or stress, for example when the plant is relocated or experiences a change in growth conditions.[11] When multiple baby plantlets are grown at the same time, it then results in the deterioration of the cluster.[11]

Harry Rose, 12 Sept 2009

Purdie, R.W. - Eriocaulon Scariosum. 31 May 2018.