Tasmanian Wildflowers: Button Grass Tullamarine, Victoria, Australia
By MAC-001 on 04-Aug-20. Waypoint GA17175

Gymnoschoenus sphaerocephalus, commonly known as button grass, is a species of tussock-forming sedge from southeastern Australia. It forms part of a unique habitat in Tasmania.

Gymnoschoenus sphaerocephalus is a perennial sedge species which forms a clump or tussock. The leaf blades reach 50 cm in length, and 0.1–0.25 cm in width. The round flowerheads arise out of the tussock, on culms which are up to a metre high. They are around 1.5–2 cm in diameter and made up of flattened spikelets 0.5 cm long. Its root system is a mass of fleshy carbohydrate-rich rhizomes, which are edible.

Gymnoschoenus sphaerocephalus grows in damp nutrient-poor soils, and in Tasmania forms a low grassland or moor in which it is the dominant shrub. Associated primitive plants include club mosses such as Lycopodiella lateralis, and Selaginella uliginosa and the ferns Gleichenia dicarpa and G. alpina. despite the wet climate, buttongrass is relatively flammable and the ecological community is adapted to regular burning. The leaves of Gymnoschoenus sphaerocephalus have the lowest recorded phosphorus content of any plant species. The soil it grows in is a peat which is acidic, with a pH of 3.5 to 4.5.

Button grass may form a symbiotic relationship with a species of burrowing crayfish Parastacoides tasmanicus, which aerates the soil with its burrows and in turn feeds on the rhizomes.

It is also a food item of the critically endangered orange-bellied parrot, which breeds in buttongrass moorlands of southwestern Tasmania over the summer.

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