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Arrowsmith spider orchid facts for kids

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Arrowsmith spider orchid
Caladenia crebra.jpg
Caladenia crebra growing near Eneabba
Scientific classification
Genus:
Caladenia
Species:
crebra
Synonyms
  • Arachnorchis crebra (A.S.George) D.L.Jones & M.A.Clem.
  • Calonema crebrum (A.S.George) Szlach.
  • Calonemorchis crebra (A.S.George) Szlach.

The Arrowsmith spider orchid (scientific name: Caladenia crebra) is a special type of orchid. It is endemic, meaning it only grows naturally in the south-west part of Western Australia. This orchid is known for its unique greenish-yellow flowers. These flowers often have thin brown "clubs" on the ends of their side petals, which makes them look a bit like a spider.

About the Arrowsmith Spider Orchid

What Does It Look Like?

The Arrowsmith spider orchid is a terrestrial plant, which means it grows in the ground. It's also a perennial plant, so it lives for more than two years. Every year, its leaves fall off (it's deciduous), but it grows back from an underground tuber (a swollen part of the stem, like a small potato).

This orchid has one hairy leaf, usually about 10 to 20 centimeters (4 to 8 inches) long and 6 to 10 millimeters (0.2 to 0.4 inches) wide.

Its Flowers

In August or September, the orchid grows one or two flowers on a stalk. This stalk can be quite tall, reaching 25 to 50 centimeters (10 to 20 inches) high. Each flower is fairly large, about 50 to 60 millimeters (2 to 2.4 inches) wide.

The flowers are mostly greenish-yellow, but sometimes they have red marks.

  • The dorsal sepal (the top petal-like part) stands upright. It's about 25 millimeters (1 inch) long and 3 to 5 millimeters (0.1 to 0.2 inches) wide.
  • The lateral sepals (the two side petal-like parts) are longer, 25 to 45 millimeters (1 to 1.8 inches) long. They can spread out or cross each other below the flower. These sepals have thin brown "clubs" on their ends, which are about 6 to 10 millimeters (0.2 to 0.4 inches) long.
  • The petals (the true petals) are 25 to 30 millimeters (1 to 1.2 inches) long and curve backwards.
  • The labellum (the special lip-like petal) is greenish-yellow. It's about 12 to 15 millimeters (0.5 to 0.6 inches) long and 10 to 12 millimeters (0.4 to 0.5 inches) wide. It has many narrow, upturned "teeth" along its sides, some with hooks!
  • In the middle of the labellum, there are many dark purplish, finger-like structures called "calli." These are packed closely together in clear rows.

After flowering, the orchid produces a dry fruit called a capsule. This capsule opens up (it's dehiscent) to release many tiny seeds.

How It Got Its Name

Scientific Naming

The Arrowsmith spider orchid was first officially described in 1971 by a scientist named Alex George. He published his description in a scientific journal called Nuytsia. The plant he described was found south of Dongara.

The second part of its scientific name, crebra, comes from a Latin word. It means "crowded." This likely refers to the "calli" (finger-like structures) that are crowded together on the flower's labellum.

Where It Lives

Habitat and Distribution

The Arrowsmith spider orchid is quite common and can be found in a wide area. It grows between the towns of Dongara and Jurien Bay in Western Australia. This area includes two special biogeographic regions (areas with similar plants and animals): the Geraldton Sandplains and the Swan Coastal Plain.

You can find this orchid growing in shallow, sandy soil. It prefers to live in low forests and areas with shrubs (shrubland).

Conservation Status

Is It Protected?

The Western Australian Government's Department of Parks and Wildlife has classified Caladenia crebra as "Not Threatened." This means it is not currently considered to be at risk of disappearing.

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