Thread-leaved sundew (Drosera filiformis) COSEWIC assessment and status report: chapter 3

Name and classification

Scientific name:

Drosera filiformis Raf.

Common name:

Thread-leaved Sundew

Family:

Droseraceae

Major plant group:

Dicotyledoneae

Description

Thread-leaved sundew is a perennial, herbaceous plant (Fernald, 1950; Gleason, 1952; Gleason and Cronquist, 1963; Zinck, 1991; Freedman et al., 1992). It has long, erect, filiform (thread-like) leaves that arise as a rosette from a roughly spherical, starchy, whitish tuber (Figure 1). There are typically 3-5 leaves per plant, each up to 11 cm long (these data are for Nova Scotia; the species grows taller in more southern parts of its range in the eastern United States). The leaves lack a distinct petiole and are covered throughout with hair-like glands that exude a sticky, colourless fluid. The glandular hairs are red-purple in colour and give the plant an overall reddish hue. The tuber is up to 5 mm wide and grows at or just under the surface of the peat substrate. The elongate, leafless flowering scape is up to 22 cm long, often with a broad crook at the apical end. The scape supports as many as 12-15 flowers, which mature sequentially from lower down on the stem to upwards. Each flower is about 1 cm in diameter and is showy with five purple petals with yellow at the base. The seeds are black, elliptic, and 0.5-0.8 mm long.

Figure 1. Thread-leaved sundew (illustrated by Annette Luttermann).

Figure 1.  Thread-leaved sundew (illustrated by Annette Luttermann).

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