Seeds of South Australia
Pterostylis aciculiformis (Orchidaceae)
Needle-point Rustyhood
List of species for Pterostylis
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Seed collecting:
September to February
Herbarium regions:
Southern Lofty, South Eastern
NRM regions:
Adelaide and Mount Lofty Ranges, South East
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. Aciculiformis from the Latin 'acicula' meaning a small pin and the suffix '-formis', possible referring to the thread-like tips of the lateral sepals. Was formally called Pterostylis  sp. Rock ledges (pl. 185, Bates & Weber 1990).
Found in the southern Mount Lofty Ranges and the South-east in South Australia, growing in drier open forest and mallee scrub, on shallow stony or gravelly soil. Also found in New South Wales and Victoria.
Native. Very rare in South Australia. Uncommon in the other states.
Plant description:
Annual terrestrial orchid growing from a tuber to 25 cm tall. Stem leaves 3–6, closely sheathing. Basal leaves of 4-7 forming a rosette, each oblong to elliptic to 30 mm long and 12 mm wide, margins entire. Inflorescence on a long erect stem with 1-12 transparent green with variable brown tonings flowers, semi-nodding. Dorsal sepal with an upcurved filiform point, labellum fleshy, oblong with a few white setae on the margins and base. A variable species but with larger flowers than Pterostylis pusilla and narrower lateral sepals than Pterostylis squamata. Flowering between September and December. 
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 liquid nitrogen.
Seed viability:
For the NVC South East Orchid Project six populations consisting of more than 7 individuals in total were recorded from the Geegeela and Bangham Conservation Parks. Approximately 2,189,000 seeds (0.67g) were banked for these seven observed populations. Seed viability ranged from 48% to 74%.