Botanical art
Prior names
Olax benthamiana
Common names
Sweetheart Leaves
Etymology
Olax from the medieval Latin 'olax' meaning ill-smelling; referring to the wood of some Asiatic species which have an unpleasant odour. Obcordata from the Latin 'cordatus' meaning heart-shaped, with the prefix ob- (reversed), referring to the shape of the leaf.
Distribution and status
Endemic to South Australia and found on the western side of Kangaroo Island and three old records in the lower Eyre Peninsula, growing on sandy soil over sheet calcrete. Native. Rare in South Australia. Presumed extinct on Eyre Peninsula.
Herbarium regions: Eyre Peninsula, Kangaroo Island
AVH map: SA distribution map (external link)
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. Fruits are green, ovoid fruit to 7 mm long, with a persistent stalk. Seeds are round, pale yellow, woody seeds to 4 mm long.
Seed collection and propagation
Collect seeds between December and January. Thorough searching is required to locate the fruits as they are usually hidden between the leaves. Collect the fruits that are large and hard. 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 is average for this species but this may depend on seed maturity when collected. This species is generally difficult to germinate, it has morphophysiological dormancy and complex germination requirements.
Fire Response
Obligate re-spouter and re-seeder. Seedlings observed as well as basal resprouting from burnt plants.
Longevity: >20 years
Time to flowering: 2 to 3 years
Recovery Work
In 2020-2021 this species was assessed post-fire in 1 year and 2 year old fire scars. A total of 1,900 seeds have been collected & banked for a population outside the 2020 fire scar. Further populations will be assessed and seeds collected on Kangaroo Island in 2021–2022. Germination screening testing the response to fire cues will be undertaken in 2021.This project was supported by the Project Phoenix program.
| Location | No. of seeds (weight grams) | Number of plants | Date collected | Collection number Collection location | Date stored | % Viability | Storage temperature |
|---|---|---|---|---|---|---|---|
| BGA | 430 (8.65 g) | 5 | 15-Dec-2008 | DJD1380 Kangaroo Island | 1-Jan-2012 | 20% | -18°C |
| BGA MSB | 900 (21 g) 1,000 (23 g) | 100+ | 17-Dec-2015 | TST1269 Kangaroo Island | 2-May-2017 | 70% | -18°C |
| BGA | 1,900 (35.470 g) | 100+ | 10-Dec-2020 | JRG766 Kangaroo Island | 28-Jun-2021 | 58% | -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.