Umbo

Definition of umbo:

part of speech: noun

A protuberance like the boss of a shield; the beak or older part of a bivalve shell.

Usage examples for umbo:

• The pileus is oval to convex and expanded, sometimes with a slight umbo or elevation at the center. "Studies of American Fungi. Mushrooms, Edible, Poisonous, etc.", George Francis Atkinson.

• The pileus is rounded, then convex, becoming nearly expanded and sometimes with an umbo "Studies of American Fungi. Mushrooms, Edible, Poisonous, etc.", George Francis Atkinson.

• The color is tawny or light yellowish with intermediate shades, darker on the umbo and becoming darker in age, sometimes umber colored, and stained with black, especially after rains where the spores are washed on the pileus. "Studies of American Fungi. Mushrooms, Edible, Poisonous, etc.", George Francis Atkinson.

• The pileus is convex, and in the young stage the margin strongly incurved, later the cap becomes expanded and has a very broad umbo "Studies of American Fungi. Mushrooms, Edible, Poisonous, etc.", George Francis Atkinson.