Australian Tropical Rainforest Orchids

Lateral sepal unification

In some orchids the lateral sepals are fused partially or for the whole length. When solidly fused the structure is termed a synsepalum. In members of the Pterostylis alliance the synsepalum is fused in the basal half but has free points. This structure can be upright or deflexed.

Lateral sepals free: the lateral sepals are separate and not fused in any way.

Lateral sepals fused fully or partially: the lateral sepals are joined for various lengths by their inner margins.