Empodisma Minus

''Empodisma minus'', commonly known as (lesser) wire rush or spreading rope-rush, is a perennial evergreen belonging to the southern-hemisphere family of monocotyledons called the Restionaceae. The Latin name ''Empodisma minus'' translates to “tangle-foot” “small”. ''E. minus'' is found from Queensland to South Australia, Tasmania and throughout New Zealand south of 38 ° latitude, or the central north island. Its current conservation status is “Least concerned”. In 2012 the new species ''Empodisma robustum'' was described in New Zealand, with what was previously described as ''E. minus'' from the lowland raised bogs of Waikato and Northland now being re-classified as ''E. robustum''. ''E. minus'' remains an important peatformer in the south of New Zealand and in high altitude peatlands.

Description

The stems are 15–200 cm long, numerously branched, semi-terete and dark green to dark brown in colour. The stem keeps upright when short, yet becomes procumbent when tall. The stem has 5.5–12 mm long sheaths that seemingly divide it to multiple segments. The sheaths are reduced leaves which keep close to the stem and have whitish axillary hairs. Spikelets, the primary inflorescence of the grass, are usually solitary and sessile in males and females, however, axillary in the males but in the upper axils in the females. The fruit of ''E. minus'' is a hard oval nut, sessile and approximately 2 mm long. The plant has a robust rhizome with a diameter of about 8 mm and numerous roots that ascend horizontally.

''E. minus'' flowers from August until December, the flowers are yellow in colour. Fruit appears from November up to March.

Distribution and habitat

''Empodisma minus'' is found most densely in the South-Eastern parts of Australia, also in Tasmania and only absent from Western Australia and the Northern Territory. The species is also present in New-Zealand. In both regions it grows from coastal to alpine areas, preferring fens, bogs, heaths, swamps and stream margins.

Ecology

The Restionaceae, which includes the family ''Empodisma'', withstands nutrient poor soils and seasonal drought. ''E. minus'' can also experience occasional fires which can be detrimental, yet the plant is able to resprout, although slowly.

In New Zealand, the species commonly grows in a thick carpet together with, for example, ''Leptospermum scoparium'' (heath shrub), ''Baumea teretifolia'' (sedge), '' Gleichenia dicarpa'' and '' Gleichenia microphylla'' (ferns) and '' Sphagnum cristatum'' (moss). ''Empodisma minus'' has been classified as the dominant species in the ombrotrophic mires of New Zealand, mainly due to its high peat-forming ability and could even be called an ecosystem engineer for fen-to-bog transitions.

In Australia, ''Empodisma minus'' is associated with '' Richea continentis'' and '' Baeckea gunniana'' (shrubs), '' Gleichenia alpina'' (fern), '' Sphagnum cristatum'' (moss) and '' Astelia alpina'' (monocotyledonous herb). The dry seasons contribute to decomposition and limited peat formation, whereas the wet seasons boost the plant’s root growth and peat accumulation.

''Empodisma minus'' is also the host plant for the larvae of the endemic New Zealand species of moth '' Aponotoreas synclinalis''.

References

{{Taxonbar, from=Q5374387

Flora of New South Wales
Flora of Tasmania
Flora of Queensland
Flora of New Zealand
Pakihi