Very small or young leaves may be atypical in shape; fully grown mature leaves should be examined whenever possible.

1. Leaves usually spreading (± prostrate or horizontal), with distinctly round to subreniform blades (at least as broad as long, excluding tentacles and slightly expanded summit of petiole); pollen (and hence mature fresh anthers) white; seeds at least 4 times as long as broad, finely striate but otherwise smooth.

D. rotundifolia

1. Leaves ± ascending or erect, with linear to obovate blades longer than broad; pollen (and hence fresh mature anthers) orange; seeds various (elongate only in D. anglica, with rough surface).

2. Blades of leaves linear (parallel-sided), 7-20 (-25) times as long as wide.

D. linearis

2. Blades spatulate-obovate or cuneate, 2-6.5 times as long as wide.

3. Scape strictly erect, arising centrally from base of plant; petioles at least sparsely pubescent or glandular; blades 3-8 mm wide.

D. anglica

3. Scape arising laterally from base of plant before curving upward; petioles glabrous; blades 2-4 mm wide (excluding spreading, stalked glands).

D. intermedia