Rhizina undulata
Description
Rhizina undulata is a species of fungus in the family Rhizinaceae. The fruit bodies are dark purple-brown with a bright yellow margin, crust-like, and attached to the growing surface by numerous root-like yellow rhizoids. It has a cosmopolitan distribution, and commonly occurs on clearings or burned areas throughout central and northern Europe, North America, northern Asia, and southern Africa.
Fruiting bodies appear in early summer and last until the first frost in the fall. The spores are dispersed by the wind and carried to the ground by rain, where they survive for at least two years. They germinate and colonize the litter and conifer roots. The fungus spreads using its mycelium, infecting and killing other seedlings. Later, fruiting bodies form on the root collar of infected seedlings and the cycle starts over again.
This mushroom is parasitic on conifer seedlings and has caused considerable damage to tree plantations worldwide.
The fungus was first described in 1774 as Helvella inflata by the German polymath Jacob Christian Schäffer. It acquired its current name in 1815 by its publication in Elias Magnus Fries's Observationes Mycologicae
Common names: Doughnut Fungus, The Pine Firefungus.
Mushroom Identification
Fruit Bodies
Up to 6 cm (2.4 in) wide, are flat, with irregular lobes, and are attached to the growing surface on the entire lower side by numerous whitish to yellowish rhizoids resembling plants roots. The hymenium is dark purple-brown to blackish, while the margin is pale yellow (like the underside), and wavy and irregular. When moist, the surface is sticky. The fruit body has a leathery texture when old. In very young fruit bodies, the surface is white; the brown color initially appears in the center and expands rapidly thereafter.
Spores
Fusiform (fuse-shaped), apiculate, minutely verricose at maturity, with one or two oil drops, and have dimensions of 30–40 by 8–11 µm. The asci are roughly cylindrical, and 250–280 by 14–18 µm. Like most other Pezizales, the asci open at maturity using an apical, lid-like flap of tissue termed an operculum. The paraphyses are slightly club-shaped, tips encrusted with tubular setae, thin-walled, brown, aseptate, and parallel-sided, tapering to a blunt point, and are 7–11 µm wide.
Similar Species
Discina ancilis is a look-alike.
Disciotis venosa has an overall similar blistered appearance, but can be distinguished by its distinct bleach-like odor. Discina ancilis bears a general resemblance to Rhizina undulata, but its fruit bodies lack rhizoids on their undersurface and are attached to the substrate at a central point.
Photo sources:
Photo 1 - Author: Alan Rockefeller (CC BY-SA 4.0)
Photo 2 - Author: Rudolphous (CC BY-SA 4.0)
Photo 3 - Author: Andreas Kunze (CC BY-SA 3.0)
Color:Brown