Spiral sun orchid (Thelymitra matthewsii)
Description
The Spiral Sun-orchid has a slender green flower stem growing to 20 cm tall. Flowers are solitary (rarely two) and bluish purple with darker stripes, its column being purplish with a bright yellow tip (Backhouse & Jeanes 1995). Thelymitra matthewsii favours open forests and woodlands in well-drained sand and clay loams. It is a post-disturbance coloniser that is usually found in open areas around old quarries and gravel pits, on road verges, disused tracks and animal trails (Backhouse & Jeanes 1995). It has been recorded as growing on gravely soils in disturbed areas of low coastal forest (Bishop 1996), in swampy soils (R.J.Bates 2000, pers. comm.), on lateritic podsol on gently sloping plateaus or from sand overlying limestone on undulating plain (Davies 1986, 1992). Flowering occurs from late Aug. to early Oct. (Backhouse & Jeanes 1995). The species is autogamous. where ovules of a flower are fertilised by pollen from the same flower, with all flowers producing seed capsules regardless of whether the flowers have opened or not (J.Jeanes 2001, pers. comm.). Reproduction is entirely from seed that is most likely ripe and dispersed four to eight weeks after flowering. The longevity of individual plants is unknown, but colonies that have been monitored show a decline in plant numbers over one or two decades (Cropper 1993). As a post-disturbance coloniser, populations have generally demonstrated a decline in the total number of plants, and the number of flowering individuals, following their initial discovery. As old colonies decline, new colonies will become established if freshly disturbed sites are available nearby. Fire may be useful to prolong the life of existing populations by reducing competition from other plants (Cropper 1993), and may also aid the establishment of new colonies.
Taxonomic tree
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Domain: Eukarya
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Kingdom: Plantae
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Phylum: Tracheophyta
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Class: Liliopsida
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Order: Asparagales
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Family: Orchidaceae
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Genus: Thelymitra
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