Nervilia concolor is a terrestrial, perennial, deciduous, sympodial herb which grows in colonies with only a few individuals producing flowers in any one year. Between two and six pale green flowers 35–40 mm (1–2 in) long and 30–35 mm (1.2–1.4 in) wide are borne on an erect flowering stem 200–350 mm (8–10 in) tall. The sepals are 17–24 mm (0.7–0.9 in) long and about 2 mm (0.08 in) wide and the petals are similar but slightly shorter. The labellum has three lobes and is cream-coloured or yellowish with hairy purple or green veins. The side lobes curl inwards and the middle lobe has wavy edges and three hairy ridges. The flowers only last up to four days, following which a single leaf develops, including on those plants that did not flower. The leaf is bright green, heart-shaped or kidney-shaped but appears almost circular, 150–250 mm (6–10 in) in diameter with wavy edges and prominent radiating veins. In Australia, flowering occurs between September and December after heavy rain but in areas north of the equator in April and May.^[2][4][5]