Thread-leaved sundew (Drosera filiformis) COSEWIC assessment and status report: chapter 7

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General

Thread-leaved sundew is a perennial, low-growing, herbaceous plant. It is an autotrophic plant, but it supplements its nutrition by carnivory (see below). It has a patchy microdistribution within its Nova Scotia habitat of raised bogs.

Reproduction

Thread-leaved sundew has insect-pollinated flowers. Anthesis begins in late July and occurs through August. There are typically about 8 capsules per flowering plant, and 70 seeds per capsule (Zinck, 1991). The seeds are probably dispersed locally by flowing water, and new plants are established as seedlings. Seedling establishment appears to be most prolific in disturbed microhabitats with bare, exposed peat. The species can also be readily transplanted as intact plants or tubers, and can be propagated vegetatively by cuttings (Lloyd 1942; Schwartz 1975; Swenson 1977; Juniper et al. 1989; Lecoufle 1991)

Survival

Thread-leaved sundew is a perennial plant, but its longevity is unknown. Most of 12 individuals transplanted to suitable coastal habitat in Halifax County, Nova Scotia, were still alive after 15 years (Wolfgang Maass, personal communication).

Movements/Dispersal

Seeds of thread-leaved sundew may be dispersed locally by flowing water.

Nutrition and Interspecific Interactions

Thread-leaved sundew is a photoautotroph that produces its own nutrition through photosynthesis. In addition, like other sundews, pitcher plants, and some other species, it is a so-called “carnivorous” plant that traps small arthropods and digests them as a source of nutrients. Thread-leaved sundew traps small animals on the sticky glands on the surface of its leaves. The animals are secured by inrolling of the leaf and digested by extracellular enzymes excreted by the sundew, and serve mainly as a source of inorganic nitrogen and phosphate (Darwin, 1875; Krafft and Handel, 1991). Because the sundew grows in an extremely oligotrophic habitat, the nutrients obtained through carnivory are important to its survival.