Plants of
South Australia
Pycnosorus pleiocephalus
Compositae
Soft Billy-buttons
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Regional Species Conservation Assessments per IBRA subregion.
Least concern
Near threatened
Rare
Vulnerable
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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 paintings: 4.

Etymology

Pycnosorus from the Greek 'pyknos' meaning dense or thick and 'soros' meaning heap, referring to the dense flowering heads of the genus.

Distribution and status

Found across the northern part of South Australia, growing in wet sandy or clayey depressions but also on stony ridges in mallee and chenopod shrubland. Also found in all mainland states. Native. Common in South Australia. Rare in Western Australia, Northern Territory and Queensland. Common in New South Wales and Victoria.
Herbarium regions: North Western, Lake Eyre, Nullarbor, Gairdner-Torrens, Flinders Ranges, Eastern, Eyre Peninsula
NRM regions: Alinytjara Wilurara, Eyre Peninsula, South Australian Arid Lands
AVH map: SA distribution map (external link)

Plant description

Erect or ascending annual herb with many stems to 40 cm high. Leaves oblanceolate to 70 mm long and 10 mm wide, acute to obtuse, surfaces olive-brown to green, with glandular and flattened hairs. Inflorescence a single ovoid or globose compound lemon-yellow heads to 20 mm long and 15 mm wide. Flowering between August and November, but probably dependent on time of rainfall. Fruits are dense pale ovoid to globular heads with numerous seeds. Seeds are brown ovoid seed to 2 mm long and 1 mm wide, covered in long white hairs. Seed embryo type is spatulate fully developed.

Seed collection and propagation

Collect seeds between September and December. Collect heads that are drying off, fluffy and turning yellow-white with hard brown seeds. Pick off whole heads or pluck off mature seeds with your fingers. Place the heads in a tray and leave to dry for one to two weeks. Then rub the heads gently by hand to dislodge the seeds. Use a sieve to separate 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. From one collection, the seed viability was low, at 45%. Seeds are non-dormant, viable seed should germinate readily.

Seeds stored:
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LocationNo. of seeds
(weight grams)
Number
of plants
Date
collected
Collection number
Collection location
Date
stored
% ViabilityStorage
temperature
BGA 
MSB
23,400 (22.49 g)
23,400 (22.49 g)
100+3-Nov-2005DJD176
Eyre Peninsula
14-Sep-200645%-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.