Major Groups > Bird's Nest Fungi


The Bird's Nest Fungi  

[ Basidiomycota > Agaricales > Agaricaceae . . . ]

by Michael Kuo

These odd and fascinating little fungi look for all the world like tiny birds' nests. The fruiting bodies form little cuplike nests which contain spore-filled eggs. The nests are called "peridia" ("peridium" in the singular), and serve as splash cups; when raindrops strike the nest, the eggs (called "peridioles") are projected into the air, where they latch onto twigs, branches, leaves, and so on. What exactly happens next is not completely clear, but eventually the spores are dispersed from the egg. They then germinate and create mycelia, which eventually hook up with other mycelia and produce more fruiting bodies.

Five genera—Crucibulum, Cyathus, Mycocalia, Nidula, and Nidularia—are included among the bird's nests. In North America the majority of the bird's nest fungi are subtropical and tropical, but a handful of species can be found north of the Gulf Coast. Identifying the bird's nest fungi is a matter of careful inspection of physical features (you may need a magnifying glass) and, occasionally, microscopic analysis.


Crucibulum laeve

Nidularia pulvinata

Key to 31 Bird's Nest Fungi in North America

1.Fungus shaped like a ball or a glob without a distinct "lid"; breaking up irregularly at maturity to expose a pile of "eggs."

1.Fungus shaped roughly like a cup or goblet that is covered with a "lid" when young (though the lid often disappears quickly); "eggs" held in a nest-like receptacle at maturity.

2.Nest fairly dark in color (dark buff to some shade of brown); nest wall granular to fuzzy; spinose hyphae present in nest wall (illustration).

2.Nest pale (whitish to pale yellowish); nest wall smooth, without spinose hyphae.

3.Eggs brown (grayish brown to reddish brown), shiny, shape ranging from platelet-like to lozenge-like or lens-like, not becoming wrinkled when dried for the herbarium; peridiole walls composed of fused, inseparable hyphae.

3.Eggs reddish brown, dull, lens-shaped, becoming wrinkled when dried; peridiole walls composed of separable hyphae.
Nidularia deformis

4.Eggs reticulate; distributed from the Gulf Coast southward.
Mycocalia reticulata

4.Eggs not reticulate.

5.Eggs chestnut brown; recorded from British Columbia.
Mycocalia denudata

5.Eggs dark blood red to blackish; recorded from the east coast of the United States.
Mycocalia duriaeana

6.Outer surface and inner surface of nest fairly smooth to the unaided eye (ignore the surface of the "lid," when present, and the upper edge of the nest, which may or may not be hairy).

6.Outer surface and/or inner surface of nest shaggy, hairy, grooved, or velvety.

7.Eggs attached to the nest with tiny cords.

7.Eggs not attached with cords.

8.Nest yellowish to yellowish brown, typically wider than 3 mm across; widely distributed.

8.Nest whitish to buff, typically smaller than 3 mm across; northern in distribution.
Crucibulum parvulum

9.Eggs mahogany brown; nest up to 6 mm high.
Nidula niveotomentosa

9.Eggs gray or light brown; nest up to 15 mm high.
Nidula candida

10.Inside surface of nest vertically lined or grooved.

10.Inside surface of nest not lined or grooved

11.Found in temperate North America (from the Gulf Coast northward).

11.Found in tropical and subtropical North America (from the Gulf Coast southward).

12.Nest with a deep brown ring around its rim; recorded from Alberta.
Cyathus annulatus

12.Not completely as above.

13.Nest typically 5-6 mm wide; montane and boreal in distribution.
Cyathus helenae

13.Nest typically 6-8 mm wide; widely distributed.

14.Nest typically 3 mm wide or smaller; eggs black; recorded from Puerto Rico.
Cyathus costatus

14.Not completely as above.

15.Nest pale gray or buff; "lid" bright white with brownish tufts of hairs; recorded from Mexico.
Cyathus bulleri

15.Not completely as above.

16.Nest dark brown, tall and slender (to 15 mm high, 5-6 mm across); eggs large (3 mm thick); recorded from Costa Rica and Jamaica.
Cyathus gayanus

16.Not completely as above.

17.Eggs sheathed; all spore dimensions about 20 µm or smaller.

17.Eggs not sheathed; spores 30-42 x 20-28 µm.
Cyathus poeppigii

18.Eggs often triangular in shape; spores 18-20 x 8-10 µm.

18.Eggs elliptical to round; spores variously sized.

19.Spores 20 x 12 µm.
Cyathus montagnei

19.Spores 6-9 x 4-7 µm.
Cyathus berkeleyanus

20.Outside surface of nest velvety or finely hairy, but not conspicuously shaggy, hairy, or scaly.

20.Outside surface of nest conspicuously shaggy, hairy, or scaly.

21.Eggs typically larger than 2 mm across.

21.Eggs typically 2 mm across or smaller.

22.Nest 10-15 mm high, 8-10 mm wide.

22.Nest to 18 mm high and 15 mm wide.

23.At least one sporal dimension regularly longer than 10 µm.

23.All sporal dimensions shorter than 10 µm.

24.Spores 12-22 x 10-12 µm; inner surface of nest silvery; tropical or subtropical in distribution.
Cyathus earlei

24.Spores 12-14 x 8-9 µm; inner surface of nest dark; recorded from the West Coast of the United States and from Chile.
Cyathus pygmaeus

25.Spores 7-9 µm; inner surface of nest white; tropical in distribution.
Cyathus canna

25.Spores 5-6 x 4 µm; inner surface of nest brownish; tropical or subtropical in distribution.
Cyathus microsporus

26.Eggs shiny and black, not sheathed; growing on dung or manured soil.

26.Eggs not shiny and black, sheathed; not growing on dung.

27.Nest golden brown darkening to blackish, 5-15 mm high; spores up to 40 µm long; widely distributed.

27.Nest pale, less than 5 mm high; spores 8 x 16 µm; recorded from Mexico.
Cyathus fimicola

28.At least one sporal dimension regularly longer than 18 µm.

28.All sporal dimensions shorter than 18 µm.

29.Nest dark buff; spores 16-22 x 12-14 µm.
Cyathus triplex

29.Nest dark purple brown to black; spores 17-24 x 10-14 µm.
Cyathus setosus

30.Spores 5-9 x 5-7 µm.

30.Spores longer and/or wider than above.

31.Nest pale buff, with a very narrow base; spores 7-15 x 4-9 µm.
Cyathus pallidus

31.Nest pale fawn to rusty, without a conspicuously narrowed base; spores 10 x 16 µm.
Cyathus intermedius


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Kuo, M. (2014, February). The bird's nest fungi. Retrieved from the MushroomExpert.Com Web site:

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