A key to the genus Hetaeria Blume
| 1. | Lip inferior; raceme 1-6 cm. long, rather densely 3-20-flowered; plant up to 20 cm. high; loaves aggregated in middle of stem; lamina lanceolate, acute, rounded or subcordate at base, 1.5-4.5 cm. long, 6-18 mm. broad; petiole and sheath 7-12 mm. long; dorsal sepal and petals 3-5 mm. long, lateral sepals a little shorter; lip 4-5 mm. long with a concave claw with 2 hooked calli at the base and 2 obovate divergent lobes at the apex | Hetaeria heterosepala |
| Lip superior; raceme 3-20 cm. long, many-flowered | 2 | |
| Lamina of lip divaricately bilobed, lobes narrowest at base, claw unthickened below lamina; outgrowths on face of column free from one another; leaves all along upper part of stem, lamina over 3 cm. long, petiole and sheath over 1.5 cm. long; raceme rather lax, 5-18 cm. long | 3 | |
| 2. | Rostellum longer than the column, 2.5-3 mm. long; leaves obliquely elliptical-ovate or ovate, 3-10 cm. long, 1.5- 4 cm. broad; inflorescence 5-15 cm. long; sepals 5-7.5 mm. long; lip 6.5 mm. long (to apex of middle lobe or central apiculus), lateral lobes 4-6 mm. long, 1.6-3 mm. broad | Hetaeria tetraptera |
| Rostellum equalling or shorter than the column, 0.9-1.2 mm. long; lobes of lip 1.5-4 mm. long | 4 | |
| 3 | Lobes of lip reflexed, oblong or narrowly oblanceolate but not much widened above, 1.5-2 mm. long; claw 3-4 mm. long, base forming two rounded sacs not projecting more than 0.5 mm. below the insertion of the lip; sepals 3-4.5 mm. long; arms of rostellum 0.9 mm. long; plant 30-45 cm. high; leaves obliquely lanceolate, lamina 9-14 cm. long, 2-5 cm. broad | Hetaeria mannii |
| Lobes of lip spreading, broadly cuneate from a narrow base, rounded at apex, 2.5-4 mm. long, 2-3 mm. broad; claw 4-5.5 mm. long, base forming two distinct rounded spurs 1-2 mm. long; sepals 4-6.5 mm. long; arms of rostellum 0.9-1.2 mm. long; plant 30-60 cm. high; leaves obliquely lanceolate or elliptical-lanceolate, lamina 6-16 cm. long, 2-5 cm. broad | Hetaeria occidentalis |
Species without a key Hetaeria vaginalis Rchb.f.,
World Checklist of Monocotyledons. The Board of Trustees of the Royal Botanic Gardens, Kew. Published on the Internet; http://www.kew.org/wcsp/monocots/ accessed 01/0/2020
