The uppermost part of the leaf is flared into a lid (the operculum), which prevents excess rain from entering the pitcher and diluting the digestive secretions within.

The upper regions are also brightly patterned with flower-like anthocyanin markings, particularly in the varieties S. flava var.

The opening of the pitcher tube is retroflexed into a 'nectar roll' or peristome, whose surface is studded with nectar-secreting glands.

Insects losing their footing on this surface plummet to the bottom of the tube, where a combination of digestive fluid, wetting agents and inward-pointing hairs prevent their escape.

This is probably an adaptation to low light levels and insect scarcity during the winter months, and shows clearly the cost of carnivory.