Key to Bird’s Nest Fungi

1. Fruit body tiny (1.5-3 mm wide), almost spherical at first; white to orange-yellow; opening to form 4-9
    star-shaped rays and exposing a single, dark spore ball (peridiole) which may be catapulted a distance
    of more than 6 m .......................................................................................................Sphaerobolus stellatus

1. Fruit body larger, typically 6-10 mm wide and high; numerous “eggs”(peridioles) contained in each
    cup (“nest”)

    2. Peridioles white; interior of cup smooth ...................................................................Crucibulum laeve

    2. Peridioles gray to grayish-brown to blackish

        3. Cup interior vertically lined or grooved; cup exterior shaggy-hairy ...........................Cyathus striatus

        3. Cup interior smooth; cup exterior finely hairy to shaggy-hairy

            4. Peridioles 2-3.5 mm wide; cup exterior finely hairy, velvety; mouth of cup
                flaring, margin often wavy.........................................................................................Cyathus olla

            4. Peridioles 1-2 mm wide; cup exterior shaggy-hairy (wooly) at least when young;
                mouth of cup not conspicuously flaring, margin typically circular.......................Cyathus stercoreus