Our species are all rather similar: somewhat delicate-looking plants with attractive pink-purple corollas falling in the afternoon, very slender linear usually scabrous leaves, and a tiny tap root. This is another hemiparasitic group, with roots attaching to diverse hosts, especially graminoids.

1. Leaves lanceolate or broader, the uppermost often with a pair of basal lobes; stem terete, with stiff retrorse hairs longer than the very short pubescence; calyx pubescent.

A. auriculata

1. Leaves narrowly linear (up to 3.5 mm wide), without basal lobes; stem usually angled (not in A. gattingeri), glabrous or antrorse-scabrous; calyx glabrous.

2. Mature pedicels 1-5.5 mm long.

A. purpurea

2. Mature pedicels 7-28 (-30) mm long.

3. Calyx tube with at most the longitudinal nerves conspicuous; plants usually blackening when dried; seeds dark brown; widest leaves often 1-3 (-3.5) mm broad.

A. tenuifolia

3. Calyx tube conspicuously reticulate-veined; plants remaining ± green when dried; seeds pale or light brown; widest leaves at most 1 mm broad.

4. Stem nearly or quite terete; corolla with 3 lower lobes pubescent outside; flowers all or mostly on branches, often appearing terminal on these.

A. gattingeri

4. Stem strongly angled (ridged); corolla with all lobes glabrous outside (though ciliate); flowers usually all or mostly on pedicels in axils of opposite leaves or bracts on the main stem (rarely branched).

A. skinneriana