Key to Species of Leptostigma; based on Fosberg (1982)
1. Plants glabrous except pilose on leaf margins; calyx lobes ovate, acute, remaining erect in fruit; temperate Chile.....Leptostigma arnottianum
1'. Plants sparsely to densely pilose, strigose, strigillose, or velutinous; calyx lobes linear to triangular or lanceolate; Australia, New Zealand, and central to northern Andes of South America.
2. Leaves densely velutinous; calyx lobes 5-6 mm long, linear; corolla ca. 15 mm long; Colombia....Leptostigma longiflorum
2'. Leaves pilose to striglose or strigillose; calyx lobes to lanceolate, 1-3 mm long; corolla 5-12 mm long; Australia, New Zealand, central to northern Andes.
3. Calyx with 2 developed lobes and 2 rudimentary lobes, these remaining erect in fruit; stipules truncate with 1-3 minute setae or teeth; Australia, New Zealand.
4. Flowers subsessile to shortly pedicellate; calyx lobes narrowly triangular, setose; corolla 8-12 mm long, on outer surface glabrous except hirsute on margins of lobes; fruit longitudinally ridged; southeastern Australia......Leptodermis reptans
4'. Flowers sessile or subsessile; calyx lobes lanceolate, entire; corolla 5-10 mm long, on outer surface hispid in upper half; fruits smooth or weakly longitudinally ridged; New Zealand.....Leptodermis setulosum
3'. Calyx with 4-6 developed lobes, these refexed in fruit; stipules triangular with 3-7 lobes or segments; central to northern Andes.
5. Leaves 9-30 x 8-25 mm; stipules with 5-7 lobes; corolla with tube 4.5-10 mm long and lobes 1-2.5 mm long; fruits 5 x 3.5 mm long.....Leptodermis pilosum
5'. Leaves 6-10 x 4-5 mm; stipules with 3-5 lobes (but see discussion of this species on its project page); corolla with tube 5-10 mm long and lobes 1-2.5 mm long; fruits 2-4 mm long.....Leptodermis weberbaueri