Pterostylis dilatata

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Robust snail orchid
Scientific classification Red Pencil Icon.png
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Monocots
Order: Asparagales
Family: Orchidaceae
Subfamily: Orchidoideae
Tribe: Cranichideae
Genus: Pterostylis
Species:
P. dilatata
Binomial name
Pterostylis dilatata
Synonyms [1]

Pterostylis dilatata, commonly known as the robust snail orchid, is a species of orchid which is endemic to the south-west of Western Australia. Non-flowering plants have a rosette of leaves but flowering plants lack a rosette and have a single green and white flower on a flowering stem with stem leaves. The flowers appear in winter and have lateral sepals which almost close off the front of the flower.

Contents

Description

Pterostylis dilatata is a terrestrial, perennial, deciduous, herb with an underground tuber and when not flowering, a rosette lying flat on the ground. Flowering plants lack a rosette but have a single green and white flower on a flowering stem 50–150 mm (2–6 in) tall with three to five stem leaves. The stem leaves are 4–20 mm (0.2–0.8 in) long and 1–4 mm (0.04–0.2 in) wide. The flower is green and white, 18–24 mm (0.7–0.9 in) long, 6–8 mm (0.2–0.3 in) wide. The dorsal sepal and petals form a hood over the column with the petals flared and the dorsal sepal having a short point. The lateral sepals are erect, fused for most of their length except for their thread-like tips which are 11–15 mm (0.4–0.6 in) long. The lateral sepals are in close contact with the gales and have a bulging sinus between them. The labellum is about 6 mm (0.2 in) long, 2 mm (0.08 in) wide and not visible outside the intact flower. Flowering occurs from May to August. [2] [3] [4] [5]

Taxonomy and naming

Pterostylis dilatata was first formally described in 1984 by Alex George from a specimen collected near Bluff Knoll. The description was published in Nuytsia. [1] The specific epithet (dilatata) is a Latin word meaning "spread out", "enlarged" or "extended" [6] referring to the bloated base of the flower. [3]

Distribution and habitat

The robust snail orchid grows in shrubland, woodland and in soil pockets on granite outcrops between Geraldton and Israelite Bay in the Avon Wheatbelt, Esperance Plains, Geraldton Sandplains, Jarrah Forest, Swan Coastal Plain biogeographic regions of Western Australia. [3] [7]

Conservation status

Pterostylis dilatata is classified as "not threatened" by the Government of Western Australia Department of Parks and Wildlife. [7]

Related Research Articles

<i>Pterostylis recurva</i> Species of orchid

Pterostylis recurva commonly known as the jug orchid, recurved shell orchid, antelope orchid or bull orchid, is a plant in the orchid family Orchidaceae and is endemic to the south-west of Western Australia. It is a relatively common orchid which has up to four jug-shaped or funnel-shaped white flowers with green and brown lines and markings. Non-flowering plants have a rosette of leaves on a short stalk.

<i>Pterostylis barbata</i> Species of orchid

Pterostylis barbata, commonly known as the western bearded greenhood or bird orchid is a species of orchid endemic to the south-west of Western Australia. Flowering plants have a rosette of leaves at the base of the plant and a single translucent white flower with dark green veins on a flowering stem with up to 20 stem leaves. It is one of a number of bearded orchids, some of which have yet to be formally described, all of which have a distinctive feather-like labellum.

<i>Pterostylis scabra</i> Species of orchid

Pterostylis scabra, commonly known as the green-veined shell orchid, is a species of orchid endemic to the south-west of Western Australia. As with similar orchids, the flowering plants differ from those which are not flowering. The non-flowering plants have a rosette of leaves but the flowering plants lack a rosette and have a single flower with leaves on the flowering spike. This greenhood has a white flower with green and pale brownish-fawn stripes and a long, curved protruding labellum. It is found in inland areas between Kalbarri and Esperance.

Pterostylis aspera, commonly known as the rough shell orchid, is a species of orchid endemic to the south-west of Western Australia. As with similar greenhoods, the flowering plants differ from those which are not flowering. The non-flowering plants have a rosette of leaves flat on the ground but the flowering plants have a single flower with leaves on the flowering spike. In this common species, the flower is white with green and reddish-brown stripes and a short, straight labellum.

Pterostylis ciliata, commonly known as the hairy rufous greenhood, tall rusthood or hairy rustyhood is a plant in the orchid family Orchidaceae and is endemic to the south-west of Western Australia. It has a relatively large rosette of leaves at its base and up to eight or more green and brown flowers which lean forward and have a small, fleshy, insect-like labellum covered with hairs.

<i>Pterostylis concava</i> Species of orchid

Pterostylis concava, commonly known as the pouched greenhood or cupped banded greenhood, is a plant in the orchid family Orchidaceae and is endemic to the south-west of Western Australia. The plants either have a rosette of leaves in the years when not flowering or stem leaves on a flowering spike. When flowering, it has up to ten or more flowers which are dark reddish-brown, sometimes green and white with deeply cupped lateral sepals. It is an uncommon orchid, mostly found between Bindoon and Mount Barker.

Pterostylis insectifera, commonly known as the insect-lipped rufous greenhood, or leaden rustyhood is a plant in the orchid family Orchidaceae and is endemic to the south-west of Western Australia. Both flowering and non-flowering plants have a relatively large rosette of leaves. Flowering plants have a similar rosette and up to eight or more flowers which have long, stiffly-held lateral sepals and a protruding, insect-like labellum.

Pterostylis macrocalymma, commonly known as the large-hooded rufous greenhood or Murchison rustyhood is a plant in the orchid family Orchidaceae and is endemic to the south-west of Western Australia. Both flowering and non-flowering plants have a relatively large rosette of leaves. Flowering plants also have up to ten or more white flowers with bold green or pale brown lines and a broad spoon-shaped, insect-like labellum.

Pterostylis platypetala, commonly known as the broad-petalled snail orchid, is a species of orchid endemic to the south-west of Western Australia. It has a rosette of leaves and when flowering, a single green and white flower with relatively wide petals. In ideal conditions it can form colonies of hundreds of plants and often grows under melaleucas on the edge of winter-wet areas.

Pterostylis rogersii, commonly known as the curled-tongue shell orchid, is a species of orchid endemic to the south-west of Western Australia. As with similar orchids, the flowering plants differ from those which are not flowering. The non-flowering plants have a rosette of leaves but the flowering plants lack a rosette and have a single flower with leaves on the flowering spike. This greenhood usually has a white and reddish-brown striped flower with a long, curved labellum and is found along the south coast between Binningup and Esperance.

Pterostylis timothyi, commonly known as the brittle snail orchid or fawn snail orchid is a species of orchid which is endemic to the south-west of Western Australia. It has a rosette of leaves at its base, and when flowering, a single green, fawn and white with erect lateral sepals.

Pterostylis brevichila, commonly known as the dwarf shell orchid, is a species of orchid endemic to the south-west of Western Australia. As with similar greenhoods, the flowering plants differ from those which are not flowering. The non-flowering plants have a rosette of leaves flat on the ground but the flowering plants have a single flower with leaves on the flowering spike. In this species, the flower is small and white with brown stripes and is similar to P. aspera but smaller in stature.

Pterostylis brunneola, commonly known as the giant snail orchid, is a species of orchid endemic to the south-west of Western Australia. Both flowering and non-flowering plants have a large rosette of leaves flat on the ground and flowering plants have a single distinctive white flower with pale fawn stripes and have leaves on the flowering spike. This species often forms large colonies, sometimes with Caladenia species.

<i>Pterostylis echinulata</i> Species of orchid

Pterostylis echinulata, commonly known as the hairy-leafed snail orchid, is a species of orchid endemic to the south-west of Western Australia. Both flowering and non-flowering plants have a compact rosette of leaves flat on the ground and flowering plants have a single pale yellowish-green flower.

Pterostylis erubescens, commonly known as the red sepaled snail orchid, is a species of orchid endemic to the south-west of Western Australia. Non-flowering plants have a rosette of leaves flat on the ground but flowering plants lack a rosette and have a single large green flower which turns reddish-brown as it ages, and has leaves on the flowering spike.

Pterostylis glebosa, commonly known as the clubbed snail orchid, is a species of orchid endemic to the south-west of Western Australia. Non-flowering plants have a rosette of leaves flat on the ground but flowering plants usually lack a rosette and have a single green and white flower with club-like lateral sepals. It sometimes forms colonies of thousands of plants.

<i>Pterostylis karri</i> Species of orchid

Pterostylis karri, commonly known as the karri snail orchid, is a species of orchid endemic to the south-west of Western Australia. Both flowering and non-flowering plants usually have a small rosette of leaves and flowering plants have a single green and white flower with unusually long, erect lateral sepals. Like some similar greenhoods, it often forms dense colonies.

Pterostylis lortensis, commonly known as the Lort River snail orchid, is a species of orchid endemic to the south-west of Western Australia. Non-flowering plants have a rosette of leaves flat on the ground but flowering plants usually lack a rosette and have a flowering stem with leaves and a single pale green and white flower with narrow, club-like lateral sepals.

Pterostylis microglossa, commonly known as the Kalbarri shell orchid, is a species of orchid endemic to the south-west of Western Australia. Non-flowering plants have a rosette of leaves flat on the ground but flowering plants lack a rosette and have a flowering stem with leaves and a single green, white and brownish-red flower.

Pterostylis orbiculata, commonly known as the coastal banded greenhood, is a plant in the orchid family Orchidaceae and is endemic to the south-west of Western Australia. The plants either have a rosette of leaves in the years when not flowering or stem leaves on a flowering spike. When flowering, it has up to twenty flowers that are reddish brown, greenish brown or green with a reddish or brownish labellum with short stiff hairs.

References

  1. 1 2 3 "Pterostylis dilatata". APNI. Retrieved 26 June 2016.
  2. Jones, David L. (2006). A complete guide to native orchids of Australia including the island territories. Frenchs Forest, N.S.W.: New Holland. p. 298. ISBN   978-1877069123.
  3. 1 2 3 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. 352. ISBN   9780980348149.
  4. Hoffman, Noel; Brown, Andrew (2011). Orchids of South-West Australia (3rd ed.). Gooseberry Hill: Noel Hoffman. p. 404. ISBN   9780646562322.
  5. Archer, William (2010-07-19). "Robust Snail Orchid - Pterostylis dilatata". Esperance Wildflowers. Retrieved 26 June 2017.
  6. Brown, Roland Wilbur (1956). The Composition of Scientific Words. Washington, D.C.: Smithsonian Institution Press. p. 743.
  7. 1 2 "Caladenia dilatata". FloraBase . Western Australian Government Department of Biodiversity, Conservation and Attractions.