Seeds of South Australia
Olax obcordata (Olacaceae)
Sweetheart Leaves
List of species for Olax
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Seed collecting:
December to January
Herbarium regions:
Eyre Peninsula, Kangaroo Island
NRM regions:
Eyre Peninsula, Kangaroo Island
IBRA regions
Kangaroo Island (KAN01)Kanmantoo
 Endangered   (IUCN: EN B2ab(i,ii,v))   (Probable Decline)   [~ 1,000 plants; long lived; only found at Cape Borda, 2 pops.]
Eyre Hills (EYB03)Eyre Yorke Block
 Endangered   (IUCN: EN B2ab(i,ii,iii); D)   (Probable 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 Olax]
Name derivation:
Olax from the medieval Latin 'olax' meaning ill-smelling; referring to the wood of some Asiatic species which have an unpleasant odour. Obcordata means inverse heart shape; referring to the shape of the leaf.
Endemic to South Australia and found on the western side of Kangaroo Island and three old records in the lower Eyre Peninsula, growing on calcrete.
Native. Rare in South Australia. Presumed extinct on Eyre Peninsula.
Plant description:
A semi-parasitic perennial shrub to 1.2 m high with round, fleshy, yellow-green, inverted heart-shaped leaves and bronze stems. Flowers are white at the axis of the leaves, appearing in spring.
Fruit type:
Green, ovoid fruit to 7 mm long, with a persistent stalk.
Seed type:
Round, pale yellow, woody seeds to 4 mm long.
Seed collecting:
Thorough searching is required to locate the fruits as they are usually hidden between the leaves. Collect the fruits that are large and hard.
Seed cleaning:
No cleaning is required. 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:
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
BGA320 (6.72 g)DJD13801-Jan-2012-18°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.