Rhizome minute, ellipsoid to spindle-shaped, 1–5 mm long, 1 mm wide; roots few, horizontal, fleshy, proliferous. Leaves usually 1 (rarely 2), almost flat on the ground. Petiole 2-7 mm long, completely subterranean, petiole bases not persistent, stipe:lamina lenght ratio 1-2.3:1. Sterile lamina minute, blue-green, becoming orange-yellow with age, oblanceolate to elliptic in outline, 1–8 × 0.3–2 mm, lenght:width ratio 1.5-2.5:1, apex rounded to broadly pointed, base attenuate, margins flat; venation simple, usually one median and two lateral veins. Fertile spike 1.5–5 cm long, fertile spike:lamina lenght ratio 6.5-11:1 with 2–7 pairs of sporangia, apex pointed.

It can be distinguished from other Ophioglossum species by its small size, the smaller sterile leaf and proportionately longer fertile spike.

thomasii: probably named after H.N.Thomas, anthropologist and plant collector.

Shallow soils in marsh or seasonally wet grasland, shallow peaty soils overlying granite or quartzite in seepage zones in deciduous woodland.

See African distribution.

Benin, Cameroon, Dem. Republic of Congo, Gabon, Ghana, Ivory Coast, Liberia, Malawi, Nigeria, Rwanda, Tanzania , Uganda, Zambia, Zimbabwe.

Terrestrial.