Caladenia dilatata
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| Caladenia dilatata is plant #1 in above image | |
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| Species: | C. dilatata
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| Caladenia dilatata | |
Caladenia dilatata, green comb spider orchid, is a deciduous terrestrial orchid species found throughout southern Australia.[1]
Morphology
Caladenia dilatata is a terrestrial orchid that consists of a single large, flower.[2] The plant itself grows 15 - 35 tall,[3] from two round tubers that are protected in a fibrous tunic.[2] It has one green basal leaf that is long and hairy.[2]
Similar to other spider orchids, the flower consists of four long, lanceolate and curved filamentous modified sepals.[3] The sepals are green-yellow, with a maroon color on the dorsal side, measuring up to 5 – 5.5 cm long.[3] They droop downwards and taper into fine, yellow-brown clubbed tips[4] that are covered with dark-colored hairs.[2] The pair of basal sepals spread away from each other, but may also curve and cross.[3]
The flower also consists of an egg-shaped green labellum that is a dark maroon on the lateral side[3] with four rows of calli towards the center.[4] The lateral margins of the labellum are green and lobed, with the lobes erect.[3] The front margins are fringed and the mid-lobe is curved downwards.
It grows in response to soaking rains, producing only a leaf that will remain dormant during the winter season.[2] However, the flower may be aborted in severely dry weather.[2]
Distribution
It is found in New South Wales, Queensland, Victoria, South Australia, as well as Tasmania.[5] Not an abundant species, it more commonly thrives in areas of high rainfall, at elevations varying between 5 – 100 meters in heathlands and coastal scrublands.[5] It can also occur in severely fragmented habitats[2] amongst rocks and granite outcrops,[3] tolerating dry, exposed environments, as well as clay, loam, sandy, and well-drained soil types.[6]
It flowers in late spring in Australia, between October and December.[1]
Reproduction
The flower closes after pollination, forming a papery capsule.[6] Yellow, brown, or black dust-sized seeds are produced in the capsule, which dries and splits open at maturity, releasing millions of seeds that are dispersed by wind or water.[6] However, the seeds only germinate upon infection by mycorrhizal fungus, and so few seeds mature into full plants.[6]
Ecology
The elongated tips of the flower produces sexual attractants and attracts pollinators in pseudocopulation, where the pollinators think the flower is a female.[2] Thynnid wasps are often attracted to the flower with the notion of copulating with the flower.[2]
Caladenia dilatata has a mutalistic relationship with mycorrhizal fungi, where the fungus acquires some nutrition from the orchid, and the orchid requires the fungus to germinate.[6] However, the orchid’s dependence on the fungus is not well known.[2]
Although the orchid’s fire ecology is not well understood, it is believed that forest fires help clear surrounding vegetation, increasing light levels and temperature at ground level.[2] With fewer competing plants, there is also believed to be an increase in moisture levels that can benefit Caladenia dilatata.[2]
Food
The indigenous name of Caladenia dilatata is koolin, and its tubers are consumed, either raw or baked,[7] by Coranderrk aboriginals.[8]
References
- ^ a b "Retired Aussies".
- ^ a b c d e f g h i j k l Todd, James A. "National recovery plan for Twelve Threatened Spider-Orchid Caladenia R. Br. Taxa of Victoria and South Australia 2000 - 2004". Australian Government Department of Sustainability, Environment, Water, Population and Communities.
- ^ a b c d e f g Cunningham, GM; Mulham, WE; Milthorpe, PL; Leigh, JH (2011). Plants of Western New South Wales. Csiro Publishing. ISBN 9780643103634.
- ^ a b "Yarra Ranges".
- ^ a b "Orchid Species".
- ^ a b c d e "Under Storey Network".
- ^ Brough, Smyth R (1878). The aborigines of Victoria: with notes relating to the habits of the natives of other parts of Australia and Tasmania. Melbourne: John Ferres, Government Printer.
- ^ De Angelis, David. "La Trobe University Environment Collective 2005" (PDF).