Dainty spider orchid

Caladenia ampla is a terrestrial, perennial, deciduous, herb with an underground tuber and a single hairy leaf, 6–10 cm (2–4 in) long and 5–7 mm (0.2–0.3 in) wide.

A single flower (rarely two) is borne on a spike up to 22 cm (9 in) high. The dorsal sepal is erect, oblong to lance-shaped, 30–37 mm (1.2–1.5 in) long and about 3 mm (0.1 in) wide. It tapers near the end which terminates in a glandular structure 6.5–9 mm (0.3–0.4 in) long. The lateral sepals are oblong to lance-shaped, 30–37 mm (1.2–1.5 in) long, 4–5 mm (0.16–0.20 in) wide and end in a gland similar to the one on the dorsal sepal. The petals are 28–32 mm (1.1–1.3 in) long, 2–3 mm (0.08–0.1 in) wide and taper to a point. The labellum is a broad egg-shape, curves forward, 14–16 mm (0.55–0.63 in) long and 10–12 mm (0.4–0.5 in) wide when flattened. The labellum is cream-coloured with red veins and a dark red tip, sometimes entirely red. There are 9 to 12 pairs of calli along the edge of the labellum, decreasing in length towards its front. There are four rows of foot-shaped calli in the centre of the labellum, also smaller towards the tip. Flowering occurs in September and October.

Caladenia ampla is only known from the goldfields region of Victoria where it grows in mallee scrub and woodlands.