Diuris micrantha

Diuris micrantha, commonly called the dwarf bee orchid[2] or tiny bee orchid,[3] is a rare species of orchid which is endemic to the south-west of Western Australia. It has four to six linear leaves at its base and up to six yellow flowers with reddish brown markings. It grows in swampy places south of Perth.

Dwarf bee orchid
Scientific classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Monocots
Order: Asparagales
Family: Orchidaceae
Subfamily: Orchidoideae
Tribe: Diurideae
Genus: Diuris
Species:
D. micrantha
Binomial name
Diuris micrantha

Description

Diuris micrantha is a tuberous, perennial herb with between four and six linear leaves, each leaf 80–130 mm (3–5 in) long and 1–2 mm (0.04–0.08 in) wide in a loose tuft at the base. Up to six yellow flowers with reddish brown markings, about 14 mm (0.6 in) long and 12–13 mm (0.47–0.51 in) wide are borne on a flowering stem 300–600 mm (10–20 in) tall. The dorsal sepal curves upwards and is narrow egg-shaped, 6–7.5 mm (0.2–0.3 in) long and about 3 mm (0.1 in) wide. The lateral sepals are linear, green and purplish, 6–10 mm (0.2–0.4 in) long, about 1.5 mm (0.06 in) wide, turned downwards and parallel to each other. The petals are more or less erect, spread apart from each other with a broadly egg-shaped to almost round blade 4–5.5 mm (0.16–0.22 in) long and 3.5–5 mm (0.1–0.2 in) wide on a reddish-brown stalk 2–3 mm (0.08–0.1 in) long. There is a distinct reddish brown blotch near the tip of the petals. The labellum is 5–7 mm (0.2–0.3 in) long and has three lobes. The centre lobe is egg-shaped to wedge-shaped, 5–7 mm (0.2–0.3 in) wide and the side lobes are linear to egg-shaped, 3–4 mm (0.1–0.2 in) long and about 2 mm (0.08 in) wide. There are two parallel, reddish brown, ridge-like calli about 3.5 mm (0.14 in) long near the mid-line of the base of the labellum. Flowering occurs in September and October.[2][3][4][5][6]

Taxonomy and naming

Diuris micrantha was first formally described in 1991 by David Jones from a specimen collected in Mandogalup, and the description was published in Australian Orchid Review.[7] The specific epithet (micrantha) is derived from the Ancient Greek words mikros meaning "small" or "little"[8]:488 and anthos meaning "flower",[8]:338 referring to the small flowers of this orchid.[4]

Distribution and habitat

The dwarf bee orchid grows with dense sedges in swampy place between Perth and Boyup Brook in the Jarrah Forest and Swan Coastal Plain biogeographic regions.[2][5][9]

Conservation

Diuris micrantha is classified as "vulnerable" under the Australian Government Environment Protection and Biodiversity Conservation Act 1999 and as "Threatened Flora (Declared Rare Flora — Extant)" by the Department of Environment and Conservation (Western Australia).[9] It is threatened by weeds and by inappropriate fire regimes, especially by fires in winter and spring.[6]

References
  1. "Diuris micrantha". World Checklist of Selected Plant Families (WCSP). Royal Botanic Gardens, Kew.
  2. Brown, Andrew; Dixon, Kingsley; French, Christopher; Brockman, Garry (2013). Field guide to the orchids of Western Australia : the definitive guide to the native orchids of Western Australia. Simon Nevill Publications. p. 227. ISBN 9780980348149.
  3. Jones, David L. (2006). A complete guide to native orchids of Australia including the island territories. Frenchs Forest, N.S.W.: New Holland. p. 124. ISBN 1877069124.
  4. Jones, David L. (1991). "New taxa of Australian Orchidaceae". Australian Orchid Research. 2: 58–59.
  5. Hoffman, Noel; Brown, Andrew (2011). Orchids of South-West Australia (3rd ed.). Gooseberry Hill: Noel Hoffman. p. 487. ISBN 9780646562322.
  6. "Approved Conservation Advice for Diuris micrantha (Dwarf Bee-orchid)" (PDF). Australian Government Department of the Environment. Retrieved 26 March 2018.
  7. "Duiris micrantha". APNI. Retrieved 26 March 2018.
  8. Brown, Roland Wilbur (1956). The Composition of Scientific Words. Washington, D.C.: Smithsonian Institution Press.
  9. "Diuris micrantha". FloraBase. Western Australian Government Department of Parks and Wildlife.
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