Seeds of South Australia
Pterostylis tenuissima (Orchidaceae)
Swamp Greenhood
List of species for Pterostylis
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Seed collecting:
December to March
Herbarium region:
South Eastern
NRM region:
South East
IBRA region
Bridgewater (NCP01)Naracoorte Coastal Plain
 Vulnerable   (IUCN: VU B1ab(iii)c(iv))   (Probable Decline)   [some populations have gone]
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 Pterostylis]
Name derivation:
Pterostylis from the Greek ‘pteron’ meaning a wing and ‘stylis’ meaning a style or column, referring to the prominent wings found at the top of the column in all species. Tenuissima from the Latin 'tenuis' meaning very slender, alluding to this species being the slenderest of all green-hoods.
Found in the coastal plains of the lower South-east in South Australia, growing in Leptospermum lanigerum scrub on alkaline soils in swamps and along the edges of rivers and creeks, often forming dense colonies. Also found in Victoria.
Native. Rare in South Australia. Rare in Victoria. Vulnerable in Australia under the EPBC Act.
Plant description:
Annual terrestrial orchid growing from an underground tuber to 30 cm tall with a single nodding flower and forming a basal rosette of 3-8 dark green, glossy ovate leaves. The basal leaves are only present when non-flowering. The flowering form has stem-sheathing leaves to 20 mm long. The single flower have a translucent, green and white striped hood to 20 mm long, labellum narrow, curved, projecting well beyond sinus. Flowering occurs throughout the year but mainly between October and February.
Fruit type:
Brown papery ellipsoid capsule.
Seed type:
Very small brown ellipsoid seed with a long  translucent brown mesh-like covering.
Seed collecting:
Collect fat capsules as they start to dry and turn brown. Pods will split and release the seeds quickly and will require monitoring. To increase the chances of collecting mature pods, it is recommended that a small breathable bag (ie. Organza bags) be used to enclose the developing capsules.
Seed cleaning:
Place the capsules in a container that will hold fine seeds and leave to dry for a few weeks or until the capsule split. Then carefully hold the capsule and tap it gently to release the seeds. 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, refrigerator or in liquid nitrogen.
Seed viability:
For the NVC South East Orchid Project one population consisting of more than 15 individuals was recorded from Pick Swamp. Approximately 16,000 seeds (0.007 g) were banked from this population. Seed viability of this collection was 65%.
Seed germination:
Seed germination in Pterostylis species is difficult in the absence of symbiotic mycorrhizal fungi.