The roughly 110 species of the Drosera genus have adapted to a variety of habitats worldwide. Both annuals and perennials, these small plants can live in soil that is poor in nitrogen and phosphorous because they eat insects. Sundews are named after the glittering leaf drops that look like dew but really are a sticky substance that snags the plants' prey.
Sundews lure insects by the way the leaves look and smell, according to Hungry Plants. The leaves vary in shape from antler-like arrangements to narrow fibers. Tentacles on their foliage discharges mucilage to snare insects. Once stuck to the plant, a bug will struggle and trigger the tentacle to bend inward and a gland to discharge acids and enzymes to digest the meal. Drosera plants draw out nourishment from the insects over the course of a day or two.
It was believed that insectivorous plants such as sundews grew flowers on long stalks to keep pollinators away from their snares. But a 2010 report in the Annals of Botany concluded the long stalks on sundews likely evolved for other reasons, such as making the flowers more viewable to pollinators. The study compared two Drosera species: one with short racemes and the other with long ones. Neither trapped any pollinator and flowers shortened by researchers attracted fewer pollinators than the long ones.
Sundews grow in tropical and moderate habitats across the globe, according to the Botanical Society of America. Often found in swamps, these plants can thrive in sandy or acidic soil. And because they eat insects, they don't face much competition where organisms such as sphagnum moss suck up soil nutrients, thus blocking the establishment of other plants, according to the Colorado Carnivorous Plant Society. Other sundew habitats include places as diverse as rainforests and deserts.
Drosera flowers follow the movement of the sun across the sky. This adaptation, called heliotropism, aids plants in several ways. For instance, it can warm flowers for the pollinators or make them easier to see. However, at least in the case of Drosera tracyi growing in Florida and neighboring states, turning east to face the rising sun likely is an anachronism that has lost its function, according to a 1994 study published in the American Midland Naturalist.