Plants of
South Australia
Roepera similis
Zygophyllaceae
White Twinleaf
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Regional Species Conservation Assessments per IBRA subregion.
Least concern
Near threatened
Rare
Vulnerable
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Extinct
Data deficient
Adelaide
Arkaroola
Ceduna
Coober Pedy
Hawker
Innamincka
Marla
Marree
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Oodnadatta
Renmark
Wudinna
Keith
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Botanical art

Kath Alcock paintings: 3

Prior names

Zygophyllum simile

Zygophyllum ammophilum, partly

Common names

White Twinleaf

Etymology

Roepera (formally Zygophyllum which is from the Greek 'zygon' meaning pair and 'phyllon' meaning leaf; referring to the pair of leaflets making up each leaf) is named after Johannes August Christian Roeper (1801 -1885), a German botanist and physician. Similis from Latin meaning similar; possibly alluding to the species similarity to Roepera ammophila, from which the species was split from.

Distribution and status

Found across South Australia except on Kangaroo Island and in the South-East, growing in a variety of habitats and on different soils. Also found in all mainland states. Native. Common in South Australia. Rare in Victoria. Common in the other states.
Herbarium regions: North Western, Lake Eyre, Nullarbor, Gairdner-Torrens, Flinders Ranges, Eastern, Eyre Peninsula, Murray, Yorke Peninsula
AVH map: SA distribution map (external link)

Plant description

Erect or ascending much-branched annual herb to 30 cm high with spreading and ascending stems. Leaves to 40 mm long, green; leaflets articulate at base, linear to narrow-oblong to 20 mm long and 4 mm wide, fleshy, apex rounded. Flowers yellow with 4 cuneate petals, apex often 3-lobed or sometimes blunt with a wavy margin. Flowering between May and December. Fruits are yellow-brown round, four segmented capsule to 7 mm long with paper wings, drooping, truncate at apex with a short point, 1 or 2 seeds per cell. Seeds are dark brown ovoid to wedge-shaped to 3 mm long and 1.5 mm wide, with a tuberculate surface. Seed embryo type is spatulate fully developed.

Seed collection and propagation

Collect seeds between August and February. Collect semi-dried and dried capsules by running your hands through the stems of the plant. Mature fruits will come off easily and will have a hard and dark seed inside each segment. Place the capsules in a tray and leave to dry for 1 to 2 weeks, depending on how green the fruit is. Then rub the dried capsules to dislodge the seeds. Use a sieve to remove the 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 is usually high.

Seeds stored:
  Hide
LocationNo. of seeds
(weight grams)		Number
of plants		Date
collected		Collection number
Collection location		Date
stored		% ViabilityStorage
temperature
BGA 
MSB		9,900 (18.25 g)
9,900 (18.25 g)		200+27-Aug-2008DJD1137
Lake Eyre		20-Jul-2009100%-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.
We acknowledge the contributions of the South Australian Seed Conservation Centre, the Botanic Gardens of South Australia, and the Department for Environment and Water.