Caladenia bicalliata, cleistogama – Limestone and Sandhill Spider Orchids

The Limestone Spider Orchid is one of the smallest flowered members of the Wispy Spider Orchid group. Its related sub species, the Sandhill Spider Orchid (C. bicalliata subsp. cleistogama) is even smaller with flowers only 2-3cm across. Both species are found only in sand dunes near the coast in scattered locations from Geraldton to Esperance and flower from August to early September.

Caladenia bicalliata subsp. bicalliata - Limestone Spider Orchid

This orchid looks similar to many other wispy spider orchids in photographs, but it is easily distinguished by its very small flowers (3-4cm across). It is found in sandy soils over coastal limestone, hence the common name.

Caladenia bicalliata - Limestone Spider Orchid

Caladenia bicalliata subsp. cleistogama - Sandhill Spider Orchid

The Sandhill Spider Orchid is distinguished from the Limestone Spider Orchid by its even smaller, paler flowers. The petals and sepals have a translucent look about them. As it is self pollinating, the flowers stay open for only a few days. Like the Limestone Spider Orchid, this species is found in sandy soils over coastal limestone.

Caladenia bicalliata subsp cleistogama

Caladenia cleistogama - Sandhill Spider Orchid