| Cooktown orchid | |
|---|---|
 | |
Scientific classification | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Monocots |
| Order: | Asparagales |
| Family: | Orchidaceae |
| Subfamily: | Epidendroideae |
| Genus: | Dendrobium |
| Species: | D. bigibbum |
| Binomial name | |
| Dendrobium bigibbum | |
| Synonyms[2] | |
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Dendrobium bigibbum, commonly known as theCooktown orchid ormauve butterfly orchid,[3] is anepiphytic orlithophyticorchid in thefamily Orchidaceae. It has cylindricalpseudobulbs, each with between three and five green or purplish leaves and arching flowering stems with up to twenty, usually lilac-purple flowers. It occurs intropical North Queensland, Australia andNew Guinea.
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There are four varieties of this orchid, each of which has previously been considered a separate species.
Dendrobium bigibbum is an epiphytic or lithophytic orchid with green or purplish pseudobulbs 200–1,200 mm (8–50 in) long and 15–20 mm (0.6–0.8 in) wide, often with purplish edges. Each pseudobulb has between three and five egg-shaped leaves 100–150 mm (4–6 in) long and 30–35 mm (1.2–1.4 in) wide. The arching flowering stems are 200–400 mm (8–20 in) long with between two and twenty lilac-purple, rarely bluish or pinkish flowers. The flowers areresupinate, 20–30 mm (0.79–1.2 in) long and 30–70 mm (1–3 in) wide, the size depending on the variety. Thesepals are oblong to egg-shaped, 20–30 mm (0.79–1.2 in) long and 9–11 mm (0.35–0.43 in) wide. Thedorsal sepal is upright or turned back and thelateral sepals spread widely apart from each other. The petals are broadly egg-shaped, 25–30 mm (0.98–1.2 in) long and wide. Thelabellum is 20–26 mm (0.8–1 in) long, 20–28 mm (0.8–1 in) wide and has three lobes. The side lobes are upright and the middle lobe has four or five ridges along its midline and a hairy patch in the middle. Flowering occurs from February to July.[3][4][5][6][7]
Dendrobium bigibbum was first formally described in 1852 byJohn Lindley and the description was published inPaxton's Flower Garden.[2][8][9]
Four varieties of this species are recognised by thePlants of the World Online:
The taxonomy of this species and of its varieties is confused, especially with respect to the scientific name of the Cooktown orchid.[11] On 19 November 1959, the Cooktown Orchid (Dendrobium bigibbum var.phalaenopsis) was proclaimed as the floral emblem of Queensland.[15] (Dendrobium bigibbum var.phalaenopsis had been originally named in 1883 byFrederick Manson Bailey, based onRobert D. FitzGerald'sDendrobium phalaenopsis.)[16] In 2015Peter Adams reduced Fitzgerald'sD. phalaenopsis to a synonym ofD. bigibbum var.superbum and this has been accepted by WCSP. Adams also reducedDavid Jones'sVappodes lithocola to a synonym ofD. bigibbum var.compactum,[17]D. phalaenopsis var.compactum toD. bigibbum var.compactum[18] andD. striaenopsis toD. bigibbum var.schroederianum.[19][20]
The Queensland government, in preparation for its 1959Centenary, sought advice as to what native species would be a good floral emblem. Specifically, the government was looking for an easily grown species found only in Queensland, which was decorative, distinctive, and close to the State colour,maroon. The Cooktown orchid, which meets these criteria, was one of the four initial suggestions, the others being the red silky oak (Grevillea banksii), the umbrella tree (Brassaia actinophylla (nowHeptapleurum actinophyllum), and the wheel-of-fire (Stenocarpus sinuatus).The Courier-Mail, aBrisbane newspaper, sought additional suggestions from its readers, and compiled a list of 13 possibilities. In a public poll, the Cooktown orchid came in first place, the red silky oak in second, and poinsettia (Euphorbia pulcherrima), already the floral emblem of the capital city Brisbane, came in third.[21]
In 1968 the Cooktown orchid was featured on an Australian postage stamp.[22]
This orchid species grows on trees and rocks in rainforest, coastal scrub, near rivers, in swamps and open forest in tropical Queensland.[10][12][13][14] The varietybigibbum also occurs in southern New Guinea[10] and var.schroederianum is found in theTanimbar Islands of Indonesia.[13]
Dendrobium bigibbum is listed as "vulnerable" under the Australian GovernmentEnvironment Protection and Biodiversity Conservation Act 1999. The main threats to the species are "settlement and visitor pressures", inappropriate fire regimes and illegal collection.[23]
It is illegal to collect the Cooktown orchid from its natural environment without a licence.[23] Commercially cultivated plants like a dry, sunny position with a minimum of watering and a temperature that does not fall below 13 °C (55 °F). Specimens need a bush-house in cooler climates.[24]
