Microtis globula

Microtis globula, commonly known as the globular mignonette orchid[2] or globular onion orchid[3] is a species of orchid endemic to the south-west coastal region of Western Australia. It has a single hollow, onion-like leaf and up to thirty five small greenish-yellow, almost globe-shaped flowers. It often grows in large colonies but only flowers after hot fires the previous summer.

Globular mignonette orchid
Scientific classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Monocots
Order: Asparagales
Family: Orchidaceae
Subfamily: Orchidoideae
Tribe: Diurideae
Genus: Microtis
Species:
M. globula
Binomial name
Microtis globula

Description

Microtis globula is a terrestrial, perennial, deciduous, herb with an underground tuber and a single erect, smooth, tubular leaf 100–250 mm (4–10 in) long and 3–4 mm (0.1–0.2 in) wide. Between eight and thirty five greenish-yellow flowers are arranged along a flowering stem 200–350 mm (8–10 in) tall. The flowers are almost globe-shaped, about 2.5 mm (0.1 in) long and wide. The dorsal sepal is egg-shaped to almost round, about 2 mm (0.08 in) long and wide and hood-like. The lateral sepals are triangular, about 2 mm (0.08 in) long, 1 mm (0.04 in) wide and curved with their upper edge partly overlapping the dorsal sepal. The petals are egg-shaped, about 1.5 mm (0.06 in) long, 1 mm (0.04 in) wide and are surrounded by the sepals. The labellum is 1.5–2 mm (0.06–0.08 in) long, about 1 mm (0.04 in) wide and lacks an obvious callus. Flowering occurs from December to January but only after a hot or late fire the previous summer.[2][3][4]

Taxonomy and naming

Microtis globula was first formally described in 1984 by Robert John Bates from a specimen collected near Walpole and the description was published in Journal of the Adelaide Botanic Gardens.[5] The specific epithet (globula) is from the Latin word "globulus" meaning "a little ball" or "globule", referring to the shape of the flowers.[2][6]

Distribution and habitat

The globular mignonette orchid grows in peaty, winter-wet areas between Albany and Northcliffe in the Jarrah Forest and Warren biogeographic regions.[2][3][7]

Conservation

Microtis globula is classified as "Priority Four" by the Government of Western Australia Department of Parks and Wildlife,[7] meaning that is rare or near threatened.[8] It is also classified as "vulnerable" under the Commonwealth Government Environment Protection and Biodiversity Conservation Act 1999 (EPBC) Act. The main threat to the species is inappropriate fire regimes.[9]

References
  1. "Microtis globula". World Checklist of Selected Plant Families (WCSP). Royal Botanic Gardens, Kew.
  2. Brown, Andrew; Dundas, Pat; Dixon, Kingsley; Hopper, Stephen (2008). Orchids of Western Australia. Crawley, Western Australia: University of Western Australia Press. p. 287. ISBN 9780980296457.
  3. Jones, David L. (2006). A complete guide to native orchids of Australia including the island territories. Frenchs Forest, N.S.W.: New Holland. pp. 224–225. ISBN 1877069124.
  4. Bates, Robert J. (1984). "The genus Microtis R.Br. (Orchidaceae): a taxonomic revision with notes on biology" (PDF). Journal of the Adelaide Botanic Gardens. 13: 60–62. Retrieved 25 February 2018.
  5. "Microtis globula". APNI. Retrieved 25 February 2018.
  6. Francis Aubie Sharr (2019). Western Australian Plant Names and their Meanings. Kardinya, Western Australia: Four Gables Press. p. 208. ISBN 9780958034180.
  7. "Microtis globula". FloraBase. Western Australian Government Department of Parks and Wildlife.
  8. "Conservation codes for Western Australian Flora and Fauna" (PDF). Government of Western Australia Department of Parks and Wildlife. Retrieved 3 April 2020.
  9. "Approved Conservation Advice for Microtis globula (South-Coast Mignonette Orchid)" (PDF). Australian Government Department of the Environment. Retrieved 25 February 2018.
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