Pitcher Plants, Sundews, and Bladderworts, OH MY!

By Kimberly Teager

Carnivorous plants evolved in environments where nutrients like nitrogen and phosphorus, required for growth, are scarce. Rather than relying on soil, they obtain these essentials from insects and other organisms using different predatory strategies and specially adapted leaves and digestive systems.

In the winter edition of shoreLINES, the article “Meet the coolest plants on the north shore” featured one such plant called Common Butterwort (Pinguicula vulgaris), but there are many more of these strange and enchanting plants to be found within Lake Superior National Marine Conservation Area (NMCA).

Newfoundland and Labrador's provincial flower, Purple Pitcher Plant (Sarracenia purpurea), is the most famous local example of a carnivorous plant. Its larger size, vibrant colours, and striking leaf and flower morphology are sure to capture your attention as easily as it captures prey. Insects attracted by the plant’s sweet-smelling and slippery nectar become trapped in a pool of water contained within its tubular leaves, while stiff downward-pointing hairs covering the interior inhibit escape. The plant then releases enzymes to dissolve its prey and absorbs the nutrients released into the water. Pitcher plants may also consume amphibians or small mammals. A 2019 study found the remains of Spotted Salamanders in one out of five Purple Pitcher Plants surveyed in Algonquin Provincial Park.

Small and delicate Sundews (Drosera spp.) are easy to miss among the mosses, but they fascinated Charles Darwin who once wrote: “At this present moment I care more about Drosera than the origin of all the species in the world.” Three Sundew species have been found in Lake Superior NMCA, including Round-leaved (D. rotundifolia), Slenderleaf (D. linearis) and Great (D. anglica) Sundews, while Spoonleaf Sundew (D. intermedia) lives in adjacent wetlands.  Their little leaves are covered in bright red hairs, each bearing a dew-like droplet of sticky fluid ready to entrap any insect that makes contact. The leaf then wraps around its catch and releases its digestive enzyme, leaving nothing but the exoskeleton behind.

Bladderworts (Utricularia spp.) are the most diverse group of carnivorous plants with ~240 species known worldwide. Species found in Lake Superior NMCA such as Common (U. vulgaris), Lesser (U. minor) and Intermediate (U. intermedia) Bladderworts are fully aquatic and free-floating, except for Horned Bladderwort (U. cornuta) which is subaquatic or terrestrial. Although not nearly as showy as other carnivorous plants, what they lack in charisma, Bladderworts make up for in speed. In fact, they are the fastest predator in the plant kingdom! The membranous traps on their feather-like leaves have hairs that detect passing aquatic organisms which they can suck up like a vacuum at forces 600 times greater than gravity; taking less than a millisecond.

Carnivorous plants may be exceptionally good at fending for themselves, but research suggests that a quarter of all carnivorous plants worldwide, including the famed Venus Flytrap, are highly vulnerable to extinction due to climate change, habitat loss or degradation, and poaching. Please be mindful of where your feet fall while out exploring Lake Superior NMCA, and don’t hesitate to share your observations on iNaturalist!