Plants of
South Australia
Gahnia clarkei
Cyperaceae
Tall Saw-sedge
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Adelaide
Arkaroola
Ceduna
Coober Pedy
Hawker
Innamincka
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Botanical art

Kath Alcock paintings: 4.

Etymology

Gahnia named after Dr. Henricus Gahn, 19th century Swedish botanist and student of Linnaeus. Clarkei named after Charles Baron Clarke (1832-1906), a British botanist who wrote several books on Cyperaceae.

Distribution and status

Found in South Australia only in the lower South-east, growing along water-courses and in swamps but can tolerate somewhat saline conditions. Also found in Queensland, New South Wales and Victoria. Native. Uncommon in South Australia. Common in the other States.
Herbarium region: South Eastern
NRM region: South East
AVH map: SA distribution map (external link)

Plant description

Tall tussock-forming perennial sedge with woody rhizomes and sprawling, elongated, cane-like culms to 2 m long. Leaf-blades flat, recurved, scabrous, mostly shorter than culms; sheaths pinkish to brown, dull or with some shining patches. Inflorescence erect and spreading with long lax branches to 125 cm long. Flowering in spring and summer. Fruits are large dark brown spike. Seeds are orange-red ovoid seed to 3.5 mm long and 2 mm wide, with a shiny and smooth surface. Seed embryo type is capitate.

Seed collection and propagation

Collect seeds between December and April. Collect heads that are dying off, turning dark brown with obvious hard orange-red seeds. Break off whole spike or collect individual spikelets. Be careful as the leaf-blades can be sharp. 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. From three collections, the seed viability was low to high, ranging from 45% to 85%.

Seeds stored:
  Hide
LocationNo. of seeds
(weight grams)
Number
of plants
Date
collected
Collection number
Collection location
Date
stored
% ViabilityStorage
temperature
BGA 
MSB
34,100 (125 g)
34,100 (125 g)
5020-Jan-2005MKJ67
South Eastern
28-Mar-200645%-18°C
BGA41,200 (195.55 g)306-Mar-2007TST171
South Eastern
1-Aug-200785%+5°C, -18°C
BGA4,000 (17.82 g)17-Jan-2008Kangaroo Flat NFR
South Eastern
20-Jul-200960%-18°C
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.