Botanical art
Prior names
Cyperus rotundus ssp. retzii
Cyperus retzii
Common names
Down's Nut-grass
Downs Flat-sedge
Downs Nut-grass
Etymology
Cyperus from the Latin 'cyperos' and derived from the Greek 'kypeiros', an ancient Greek name used by Homer and Theophrastus for several plants of this genus. Bifax from the Latin 'bifax' meaning with two faces, alluding to the species similarity to other Cyperus species.
Distribution and status
Found scattered in north-east South Australia growing on floodplains on heavy clay soils. Also found in all mainland States. Native. Rare in South Australia. Rare in Victoria. Common in the other States.
Herbarium regions: Lake Eyre, Flinders Ranges
AVH map: SA distribution map (external link)
Plant description
Perennial sedge to 75 cm high with wiry rhizomes bearing prominent, ellipsoid, fibrous-coated tubers. Stems slender, triquetrous throughout. Leaves grass-like, narrow, usually shorter than the stems; bracts 2-4, the lower about as long as or longer than the inflorescence. Inflorescence a simple umbel with 4-8 slender rigid rays. Spikelets brown with 12-24 flowers, close together in small spikes of 3-10. Flowering between April and August. Fruits are orange fruit-head in loose clusters at the tips of erect triangular stems. Seeds are brown ovoid triangular seed to 1.5 mm long and 1 mm wide, with fine creamy reticulate outer coating. Seed embryo type is capitate.
Seed collection and propagation
Collect seeds between May and October. Collect fruits by picking off the mature heads, those turning an orange colour and come-off easily. 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 one collection, the seed viability was high, at 100%. Seeds are non-dormant, viable seed should germinate readily.
| Location | No. of seeds (weight grams) | Number of plants | Date collected | Collection number Collection location | Date stored | % Viability | Storage temperature |
|---|---|---|---|---|---|---|---|
| BGA | 6,500 (2.16 g) | 10 | 11-May-2008 | RJB77863 Lake Eyre | 19-Sep-2008 | 100% | +5°C, -18°C |
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.