Seeds of South Australia
Tribulus astrocarpus (Zygophyllaceae)
Star-head (Walytjapiri)
List of species for Tribulus
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Seed collecting:
May to December
Herbarium regions:
North Western, Lake Eyre
NRM regions:
Alinytjara Wilurara, South Australian Arid Lands
IBRA regions
Kintore (GVD04)Great Victoria Desert
 Near Threatened
Breakaways (STP01)Stony Plains
 Near Threatened
Witjira (STP06) 
 Near Threatened   [edge of range]
Everard Block (CER03)Central Ranges
 Near Threatened
Pedirka (FIN04)Finke
 Least Concern
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 Tribulus]
Name derivation:
Tribulus from the Greek 'tribolos' meaning water-chestnut and translated into Latin as 'tribulos' which originally meant the caltrop, a 4-pointed military instrument, employed to lame advancing cavalry, and the name also applied to Tribulus terrestris. Astrocarpus from the Greek 'astron' meaning a star and 'karpos' meaning a fruit; alluding to the star-shaped fruit.
Distribution:
Found in the north and north-western parts of South Australia, growing on red sandy soil in river flats, drainage lines and flats. Also found Western Australia, Northern Territory and Queensland.
Status:
Native. Uncommon in South Australia. Common in the other states.
Plant description:
Prostrate hairy annual herb. Leaves alternate, with 3-6 pairs of leaflets, leaflets ovate-cuneate or oblong to 10 mm long. Flowers yellow to 8 mm diameter with 5 petals that slightly exceeding the calyx. Flowering between March and October.
Fruit type:
Woody star-shaped fruit to 25 mm across with 5 rigid horizontally spreading spines, splitting into 5 segments, each bearing 2 halves of the spines of 2 adjacent carpels.
Seed type:
2 seeds contain in the basal part of each woody fruit segment.
Embryo type:
Spatulate fully developed.
Seed collecting:
Collect fruits that are hard and brown. Some fruits maybe split and laying on the ground.
Seed cleaning:
No further cleaning is required if only fruits are collected. 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 high, at 90%.
Seed germination:
This species have physical and physiological dormancies that needs to be overcome for the seed to germinate.
Seeds stored:
LocationNo. of seeds
(weight grams)
Number
of plants
Date
collected
Collection number
Collection location
Date
stored
% ViabilityStorage
temperature
BGA 
MSB
1900 (65 g)
1900 (65 g)
319-May-2007RJB71961
Lake Eyre
1-Aug-200790%-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.