Asterella gracilis has a rigid, dark or light green thallose gametophyte, which can be purple-ish on the margins.

The upper surface is somewhat bulging, with complex pores and one layer of elongated air chambers; the thallus is thicker in the center.

The abaxial surface is purple-ish to black, with scales forming a row on either side of the thickened center.

The archegonial receptacle stalk is around 3cm tall and arises in a notch at the thallus apex; the receptacle is "hemispherical to conic, green to purplish tinged, 3-4 lobed, with conspicuous white membranaceous long-lanceolate pseudoperianth divisions surrounding each hemispherical blade sporangium that opens by an operculum.

Asterella gracilis is found in Europe, western North America, Alaska, Alberta, BC, Montana, Oregon, Mexico and South America.