Seeds of South Australia
Olearia microdisca (Compositae)
Small-flower Daisy-bush
List of species for Olearia
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Seed collecting:
March to April
Herbarium region:
Kangaroo Island
NRM region:
Kangaroo Island
IBRA region
Kangaroo Island (KAN01)Kanmantoo
 Vulnerable   (IUCN: VU D2)   (Probable Increase)   [lots of recent records; responds to fire; have been replanting & lighting fires to manage sp; has increased]
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 Olearia]
Name derivation:
Olearia named after Johann Gottfried Ölschläger (1603-1671), a German horticulturist and author of a flora of Halle in Germany (his name was Latinised to Olearius). Microdisca from the Greek 'mikros' meaning small and  'diskos' meaning disk, referring to the small numbers of disk florets compared to ray florets.
Distribution:
Endemic to South Australia and found only on the eastern side of Kangaroo Island, growing in low lying areas subject to seasonal waterlogging such as along creek banks and gilgais in open mallee woodland and shrubland with Eucalyptus cneorifolia and/or E. cosmophylla. Olearia microdisca is an early successional species and the majority of the populations is found in areas regenerating from a significant disturbance event such as vegetation clearing or fire.
Status:
Native. Very rare in South Australia.
Plant description:
Compact shrub to 1.5 m high with erect, woody, much-branched, finely pubescent stems. Leaves sessile, approximate and sometimes overlapping, upcurved to appressed, oblong, with a prominently obtuse base, to 2.5 mm long and 1 mm wide, thickened, glabrous above, tomentose below without prominent veins, margin entire, revolute. Inflorescence solitary, sessile, terminal on erect branchlets sometimes forming a very loose leafy panicle with 2-5 white ray florets and 2-3 yellow disk florets. Flowering between October and February.
Fruit type:
Small fluffy daisy heads containing numerous seeds.
Seed type:
Striated brown seed to 1.5 mm long and 1 mm wide, covered in rows of hairs and with a ring of pappus bristles to 2 mm long.
Embryo type:
Spatulate fully developed.
Seed collecting:

Collect heads that are large and fluffy. Either pick off the whole heads or use your finger and pull off the seeds from the head. Mature seeds will come off easily.

A field collecting trip to Kangaroo Island in April 2017 will aim to collect and bank at least three populations of this endangered daisy with the support of the Australian Seed Bank Partnership

Germination table:
DateResultT0T50Pre-treatment | Germination medium | Incubator: Photoperiod / Thermoperiod
May-1733%21NA 500 mg/L gibberellic acid for 24 h;
1% agar;
Incubated under winter conditions
May-1730%14NA 500 mg/L gibberellic acid for 24 h;
1% agar;
Incubated under spring/autumn conditions
Oct-157%28 dNA 500 mg/L gibberellic acid 48 h;
1% agar;
Incubated under spring/autumn conditions
Oct-157%21 dNA 500 mg/L gibberellic acid 48 h;
1% agar;
Incubated under winter conditions
Result: Maximum percentage of germination observed.
T0: Number of days before first germinant observed.
T50: Number of days to achieve 50% germination.
Pre-treatment: The initial treatment that the seeds received prior to placement on germination media.
Germination medium: The substrate that seeds were placed on for the duration of the germination experiment.
Incubator conditions:
Photoperiod: The duration of light exposure that the seeds were subject to during a 24 hour period.
Thermoperiod: The constant or diurnal temperatures that seeds were subject to during a 24 hour period.
Winter conditions: 15°C 20 h (3am→11pm); 5°C 4 h (11pm→3am) / 10 h light (8am→6pm); 14 h dark (6pm→8am)
Spring/Autumn conditions: 22°C 12 h (8am→8pm); 10°C 12 h (8pm→8am) / 12 h light (8am→8pm); 12 h dark (8pm→8am)
Summer conditions: 30°C 14 h (6am→8pm); 15°C 10 h (8pm→6am) / 14 h light (6am→8pm); 10 h dark (8pm→6am)