Seeds of South Australia
Microtis orbicularis (Orchidaceae)
Swamp Onion-orchid
List of species for Microtis
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Seed collecting:
November to January
Herbarium regions:
Eyre Peninsula, Southern Lofty, Kangaroo Island, South Eastern
NRM regions:
Adelaide and Mount Lofty Ranges, Eyre Peninsula, Kangaroo Island, South East
IBRA regions
Glenelg Plain (NCP02)Naracoorte Coastal Plain
 Endangered   (IUCN: EN B2ab(i,ii,iii))   (Definite Decline)   [needs water; drying a huge threat]
Lucindale (NCP03) 
 Endangered   (IUCN: EN B2ab(i,ii,iii))   (Definite Decline)   [needs water; drying a huge threat]
Kangaroo Island (KAN01)Kanmantoo
 Endangered   (IUCN: EN B2ab(i,ii,iii,iv,v))   (Definite Decline)
Fleurieu (KAN02) 
 Endangered   (IUCN: EN B2ab(i,ii,iii); D)   (Definite Decline)   [possibly extinct]
Eyre Hills (EYB03)Eyre Yorke Block
 Endangered   (IUCN: EN B2ab(i,ii,iii))   (Definite Decline)   [salination of waterholes a threat]
Murray Mallee (MDD02)Murray Darling Depression
 Regionally Extinct   [presumed extinct; land now grazed]
Lowan Mallee (MDD04) 
 Endangered   (IUCN: EN B2ab(i,ii,iii))   (Definite Decline)   [lack of water]
Wimmera (MDD05) 
 Endangered   (IUCN: EN B2ab(i,ii,iii))   (Definite Decline)   [needs water; drying a huge threat]
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 Microtis]
Name derivation:
Microtis from the Greek 'mikros' meaning small and 'otos' meaning ear, referring to the small ear-like column wings. Orbicularis from the diminutive form of the Latin 'orbis' meaning circle, ring or disk, referring to the almost circular lower part of the labellum.
Distribution:
Found at the bottom of Eyre Peninsula, Kangaroo Island, southern Mount Lofty Ranges and the lower South-east in South Australia, growing in areas subject to periodic inundation such as swamps, soaks, wet depressions in heath and heathy woodland. Also found in Western Australia, Victoria and Tasmania.
Status:
Native. Rare in South Australia. Uncommon in Victoria and Tasmania. Common in Western Australia.
Plant description:
Annual terrestrial orchid growing to 30 cm tall with up to 30 tiny flowers. It has a single green or reddish terete leaf to 25 cm long and 3 mm wide. Flowers emerge from the just below the leaf apex, are green to reddish-brown, shortly stalked and arranged spirally. The labellum is smooth and rounded and lacks calli, the dorsal sepal broadly ovate, 2 mm wide. Flowering between September and November.
Fruit type:
Brown papery ellipsoid capsule.
Seed type:
Very small dark brown, long ellipsoid seed with a long cylindrical translucent dark 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 a total of four populations consisting of more than 400 individuals were recorded from Topperwien Native Forest Reserve, Geegeela and Bangham Conservation Parks. Approximately 2,080,000 seeds (2.15 g) were banked for these four observed populations. Seed viability ranged from 50% to 68%.
Seed germination:
More research is needed to understand the requirements of seed germination in Microtis species.