Drosera filiformis Raf.

Taxonomy and Common Names

Drosera filiformis Raf., commonly known as Tracy's sundew, dewthread, or the thread-leaved sundew, is a small, insectivorous, rosette-forming perennial herb species.

Leaf Characteristics

As a sundew, it is unusual within its genus: its long, erect, thread-like (filiform) leaves unroll in spirals, an arrangement similar to the circinate vernation found in ferns.

Native Geographic Range

Drosera filiformis grows naturally in both Canada and the United States. Its natural range runs along the eastern seaboard of North America, from southwestern Nova Scotia in the north, through New England, to Florida in the south.

Distribution Origin Explanation

Its disjunct distribution along the Atlantic Coast reflects the prehistoric land connection between Nova Scotia and Cape Cod, Massachusetts. This connection formed an ancient extension of the Atlantic Plain region that likely persisted as an island chain well into the current interglacial period.

Gulf Coast Population Status

Drosera filiformis is also found on the Gulf Coast from Florida to Louisiana, though this Gulf Coast population may actually represent Drosera tracyi.

Cultivation and Cultivars

Drosera filiformis is frequently cultivated, and has a few registered cultivars, including D. filiformis var. filiformis (also called D. filiformis typical), and D. filiformis × 'California Sunset', a hybrid of D. filiformis var. filiformis.

Cultivation Soil and Water Requirements

All of these cultivars are grown under conditions similar to most other Drosera species, requiring mineral-poor soil and water from distilled, reverse osmosis, or collected rain sources.

Winter Dormancy Trait

For long-term survival, Drosera filiformis needs a winter dormancy, and forms hibernacula during the winter.