Cup Fungi

Microstoma floccosa & Crucibulum laeve
Monday, July 11, 2011

Microstoma floccosum

This first cup fungus is quite distinctive. Sometimes called “Shaggy Scarlet Cup,” it is shaped like a cup or goblet about 1 cm wide. The inner, fertile surface (where the spores are produced) is a bright scarlet color and smooth. The outer, sterile surface is red as well, but always coated in dense white hairs which make this species easy to identify. The stem is relatively long for a cup fungus—3-5 cm long—and also bears thick white hairs.  

Like many fungi, Microstoma floccosa is saprobic; it leeches nutrients and energy out of decaying plant or animal matter. This species prefers decaying hardwood sticks or logs on the forest floor to colonize. It produces its distinctive fruiting bodies in the summertime. It is found usually east of the Rocky Mountains, primarily in the southeast US.

Microstoma floccosa is an ascomycete, meaning that its spores are produced inside specialized cells called asci. These are differentiated from basidiomycetes, which produce their spores outside specialized cells called basidia. Basidiomycetes constitute most “fleshy” fungi, including gilled mushrooms and pored mushrooms. Fungi such as yeasts, mildews and molds are all ascomycetes. However, a few “fleshy” fungi are ascomycetes as well; these include morels, saddle fungi, and cup fungi.


Bird’s Nest Fungus

Crucibulum laeve

            This second cup fungus is one among many distinct species which are called by the common name of “Bird’s Nest Fungus.” The origin of this name is obvious—the cup-shaped fungi are often filled with tiny “eggs,” causing them to closely resemble minute birds’ nests. The cup of this fungus is 5-8 mm high and up to 15 mm in diameter. It is initially round and closed at the top, however, as it matures, it opens into the “nest” shape. The smooth or velvety outer surface of the nest can be yellowish to brownish colored. The inner surface is quite smooth or shiny, and is usually white-to-grayish colored. Bird’s Nest Fungi usually contain a number of pale “eggs.” These are shaped like ellipses and rarely exceed 2 mm in diameter. They are attached to the nest by minute cords, called funiculi.

            The function of these “eggs” is simple—rather like the function of a real egg. When a raindrop falls into the cup, the eggs are projected out of the cup, breaking the fragile cords which had tied them to it. The cord remains with the egg. The end of the tiny cord, where it has broken, is sticky; this adheres to a twig, branch, or leaf and stops the flight of the egg. The egg then swings back and attaches itself to whatever substrate it has found. From this point, the egg gradually disperses spores into the air, which germinate on the ground and create mycelia. When two mycelium of different strains, or “sexes,” hook up, they produce new fruiting bodies.

             Crucibulum leave are saprobic and can be found growing solitarily or in clusters on most woodland debris. They fruit in the spring through fall, and occur across most of North America.

Articles by Hazel Galloway