Plants of
South Australia
Olearia microdisca
Compositae
Small-flower Daisy-bush
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Regional Species Conservation Assessments per IBRA subregion.
Least concern
Near threatened
Rare
Vulnerable
Endangered
Critically endangered
Extinct
Data deficient
Adelaide
Arkaroola
Ceduna
Coober Pedy
Hawker
Innamincka
Marla
Marree
Mount Gambier
Oodnadatta
Renmark
Wudinna
Keith
Yunta
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Botanical art

Kath Alcock painting: 1.

Etymology

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 and status

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. Native. Very rare in South Australia.
Herbarium region: Kangaroo Island
NRM region: Kangaroo Island
AVH map: SA distribution map (external link)

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. Fruits are small fluffy daisy heads containing numerous seeds. Seeds are 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. Seed embryo type is spatulate fully developed.

Seed collection and propagation

Collect seeds between March and April.

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

Seeds stored:
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LocationNo. of seeds
(weight grams)
Number
of plants
Date
collected
Collection number
Collection location
Date
stored
% ViabilityStorage
temperature
 
MSB

33,000 (7.5 g)
446-May-2004DT16
Kangaroo Island
BGA5,600 (0.72 g)19-Apr-2013KI2013
Kangaroo Island
1-Jan-201610%-18°C
BGA22,000 (28.1 g)~504-Apr-2017MH34
Kangaroo Island
1-Nov-201755%+5°C, -18°C, -80°C
BGA60,000 (36.36 g)60+6-Apr-2017MH35
Kangaroo Island
1-Nov-201780%+5°C, -18°C, -80°C
BGA65,000 (45 g)1353-Apr-2017MH33
Kangaroo Island
1-Nov-201780%+5°C, -18°C, -80°C
BGA72,000 (21.7 g)6012-Apr-2017MH36
Kangaroo Island
1-Nov-201725%+5°C, -18°C, -80°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.
Germination table:
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