Carousel spider orchid

Caladenia arenicola is a terrestrial, perennial, deciduous, herb with an underground tuber and a single erect, hairy leaf 15–25 cm (6–10 in) long and 5–12 mm (0.2–0.5 in) wide. The inflorescence is a raceme, 30–60 cm (10–20 in) high with up to three flowers, each flower 8–10 cm (3–4 in) long and 6–8 cm (2–3 in) wide. The dorsal sepal is erect and the lateral sepals and petal spreads widely and have narrow scent-producing glands on their ends. The labellum is more than 11 mm (0.4 in) wide with long calli along its edges and calli along its centre in four or more roughly parallel rows. Flowering occurs between late August and October and is followed by a non-fleshy, dehiscent capsule containing a large number of seeds.

Carousel spider orchid occurs between Lancelin and Yarloop in the Jarrah Forest and Swan Coastal Plain biogeographic regions where it grows in sandy soil in Allocasuarina, Eucalyptus or Banksia woodland.