Plants of
South Australia
Machaerina laxa
Lax Twig-sedge,
Lax Twig-rush
Display all 21 images
Regional Species Conservation Assessments per IBRA subregion.
Least concern
Near threatened
Critically endangered
Data deficient
Coober Pedy
Mount Gambier
Enlarge Map
Copy Map
Copy Map
Display IBRA region text

Botanical art

Kath Alcock paintings: 2

Prior names

Baumea laxa

Machaerina gracilis

Cladium laxum

Cladium gracile

Chapelliera laxa

Common names

Lax Twig-sedge

Lax Twig-rush


Machaerina from the Latin 'machaera' meaning a bent dagger or sword, and the feminine diminutive suffix '-ina", referring to the shape of the leaves of some species (formally Baumea named after Antoine Baume (1728 - 1804), a French chemist and inventor). Laxa from Latin meaning loose or slack, alluding to its weeping habit.

Distribution and status

Found on Kangaroo Island, southern Mount Lofty Ranges and lower South-east in South Australia, growing on edge of swamp. Also found in Western Australia and Victoria. Native. Rare in South Australia. Uncommon in the other States.
Herbarium regions: Southern Lofty, Kangaroo Island, South Eastern, Green Adelaide
NRM regions: Adelaide and Mount Lofty Ranges, Kangaroo Island, South East
AVH map: SA distribution map (external link)

Plant description

Perennial sedge with stems to 60 cm long and 8 mm wide, striate, very flat with acute edges or one side somewhat concave. Leaves all basal and similar to the stems. Flowers in solitary spikelets in narrow, very loose interrupted panicle, about half the length of the plant. Flowering between October and May. Fruits are narrow, brown heads at the tip of stems. Seeds are smooth, brown ovoid nut to 6 mm long and 3 mm wide. Seed embryo type is capitate.

Seed collection and propagation

Collect seeds between December and February. Collect whole heads that are brown, containing dark hard seeds. Not all heads will contain seeds. Place the heads in a tray and leave to dry for one to two weeks. Then rub the heads with a rubber bung to dislodge the seeds. Use a sieve to separate any unwanted material. Store the seeds with a desiccant such as dried silica beads or dry rice, in an air tight container in a cool and dry place available. Seed viability is variable depending on maturity of seeds when collected. This species is generally difficult to germinate, it has morphophysiological dormancy and complex germination requirements.

Fire response

Obligate re-spouter and re-seeder.

Longevity: >20 years

Time to flowering: 1 year for re-sprouting plants

Recovery work

In 2020-2021 this species was assessed post-fire in 1 year old fire scars. A total of 11,700 seeds have been collected & banked for a population inside the 2020 fire scar. Germination screening testing the response to fire cues will be undertaken in 2021.This project was supported by the Emergency Seed Collecting Fund, a grant awarded to the Australian Seed Bank Partnership by the Royal Botanic Gardens, Kew on behalf of the UK Government..

Seeds stored:
LocationNo. of seeds
(weight grams)
of plants
Collection number
Collection location
% ViabilityStorage
7,500 (42.75 g)
7,500 (42.75 g)
Southern Lofty
1-Aug-2007100%+5°C, -18°C
BGA11,700 (12.770 g)100+12-Jan-2021JRG774
Kangaroo Island
28-Jun-202195%-18°C, -80°C
BGA1,000 (1.185 g)15-Feb-2023BKB182
South Eastern
Location: BGA — the seeds are stored at the Adelaide Botanic Gardens, MSB — the seeds are stored at the Millennium Seed Bank, Kew, England.
Number of plants: This is the number of plants from which the seeds were collected.
Collection location: The Herbarium of South Australia's region name.
% Viability: Percentage of filled healthy seeds determined by a cut test or x-ray.