Seeds of South Australia
Baumea tetragona (Cyperaceae)
Square Twig-sedge
List of species for Baumea
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Seed collecting:
November to March
Herbarium regions:
Southern Lofty, Kangaroo Island, South Eastern
NRM regions:
Adelaide and Mount Lofty Ranges, Kangaroo Island, South East
IBRA regions
Mount Gambier (SVP02)Southern Volcanic Plain
 Vulnerable   (IUCN: VU D2)
Bridgewater (NCP01)Naracoorte Coastal Plain
 Regionally Extinct   [possibly extinct]
Kangaroo Island (KAN01)Kanmantoo
 Vulnerable   (IUCN: VU B2ab(i,ii,iii))   (Probable Decline)   [blue gum plantations, herbicides, pigs - threats]
Fleurieu (KAN02) 
 Near Threatened   (Probable Decline)   [habitat quality decline]
Mount Lofty Ranges (FLB01)Flinders Lofty Block
 Near Threatened   (Probable Decline)   [habitat quality decline]
RSCA map:
Regional Species Conservation Assessments per IBRA subregion. Please click the thumbnail map.
AVH map:
Australian distribution map (external link)
SA Census:
Census of South Australian plants (external link)     [genus Baumea]
Name derivation:
Baumea named after Antoine Baume (1728–1804), a French chemist and inventor. Tetragona from the Greek 'tetra' meaning four and 'gonia' meaning an angle, referring to the square cross section of the stem.
Found on Kangaroo Island, southern Mount Lofty Ranges and the lower South-east in South Australia, growing in swamps. Also found in Queensland, New South Wales, Victoria and Tasmania.
Native. Uncommon in South Australia. Rare in Queensland. Common in the other States.
Plant description:
Perennial sedge with slender stems to 120 cm long and 2 mm wide; prominently 4-angled in the upper part, often compressed or subterete in the lower part. Leaves all basal, acutely 4-angled, much wider and sometimes as long as the stem, the tip very acute; inner leaves often reduced to the sheath with lowest bract reduced to its sheath. Flowers in dense panicles with crowded brown-black spikelets. Flowering between spring and summer.
Fruit type:
Dense brown-black heads at the tip of stems.
Seed type:
Pale yellow-brown ovoid nut to 2 mm long and 1 mm wide, with a wrinkled surface.
Embryo type:
Seed collecting:
Collect whole heads that are brown, containing dark hard seeds. Not all heads will contain seeds.
Seed cleaning:
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.
Seed viability:
Not all mature seeds are viable. From one collection, the seed viability was average, at 70%.
Seed germination:
This species is generally difficult to germinate, it has morphophysiological dormancy and complex germination requirements.
Seeds stored:
LocationNo. of seeds
(weight grams)
of plants
Collection number
Collection location
% ViabilityStorage
BGA20500 (15.38 g)7-Dec-2006RJB70682
Southern Lofty
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.