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. |