Figure 5. Stages (A, B, C, D) in egg dispersal in bird’s nest fungi. Image supplied by Professor Nicholas Money, Miami University, Oxford, Ohio as found in Hassett et al., 2013;
https://www.sciencedirect.com/science/article/pii/S1878614613001165.
ground below (Martin, 1927). Although Martin’s follow-up lab experiments proved his deductions, his research was largely ignored. It was not until the early 1940s and the experimental work of American mycologist Arthur Buller and later by Harold Brodie that questions around BNF egg dispersal mechanism were finally answered (Brodie 1975; Hassett et al., 2013). In Buller’s explanation, the nests are
called “splash cups,” a label used in some bryophytes that rely on water for sperm and gemma dispersal and indicative of the importance nest shape plays in spore dispersal (Brodie, 1975). As Brodie explains and Money’s diagram illustrates, the process begins when a raindrop, or a waterdrop falling from overhead vegetation, strikes the rim of a mature nest (Fig: 5A). Te cup’s funnel shape directs the drop and a proportion of its kinetic energy toward the nesting eggs. Tis energy and the resulting backsplash combine to dislodge one or more eggs from the nest. Tis forceful action separates the egg’s purse from the sheath and the middle piece from the nest wall. Now free, the egg travels in a parabolic trajectory a meter or two away from the nest (Fig. 5B). During the flight, the funicular cord either remains coiled within the purse or uncoils and trails the ejected egg. If a stem, leaf, or other plant debris lies in the path of the egg’s trajectory, the sticky hapteron snags it (Fig. 5C). Te egg’s forward momentum then swings it around the plant like a tetherball to firmly hold the egg in place. If the momentum is insufficient, the snagged egg might simply dangle like a pendant from the plant (Fig. 5D). Species that lack a funicular cord (namely those
12 FUNGI Volume 19:2 Summer 2026
of Mycocalia, Nidula, and Nidularia), have eggs covered in mucilage that holds them fast to impacted surfaces (Brodie 1975; Hassett et al., 2013). If you find a nest with missing eggs, you are likely to find the eggs stuck to or hanging from nearby vegetation or other nearby standing objects. Given that the entire egg ejection takes
less than a second, it was not until the use of high-speed photography in the late 1950s that the egg process could be seen and Buller’s and Brodie’s explanation confirmed (Hassett et al., 2013). A high-speed video capturing the process was filmed by Maribeth Hassett and Mark Fischer in Nicholas Money’s lab at Miami University of Ohio in 2011. It can be viewed on YouTube (https://www.
youtube.com/watch?v=EGlaQhDi5ts). (Alert—make sure your speaker volume is turned down!)
Spore Dispersal
and Germination Spore dispersal via splash cups and
domestic animal vectors are mostly local to regional in scale. Long-range dispersal likely occurs via migrating birds, nests on rafting wood, and anthropogenic activity. In a 2021 sequencing study, Cyathus specimens collected from North America, Europe, and New Zealand were deemed to be genetically alike, something the authors considered unusual given the distances between sample sites. Tis genetic likeness, they explained, was likely due to the agricultural and horticultural practices of shipping exotic plants, mulch, and soil that contain BNF eggs, spores, or living mycelium internationally
(Kraisitudomsook et al., 2021). Once the eggs are ejected from a nest,
the spores must be freed and deposited in an appropriate habitat if they are to have any chance of germinating. In many cases, eggs stuck to vegetation are eaten by grazing animals. In dung- loving species like C. stercoreus, the eggs require temperatures around 40O
to germinate and take advantage of the warm digestive tracts of animals, and later the animals’ feces as substrates, to “sprout” and produce new nests. Although C. stercoreus is commonly
seen in domestic animal pastures and manured soils used in gardens, this incubated germination likely occurs in fields and forests grazed by wild herbivores too. Eggs that do not require grazing to germinate likely dry out where they hang. As the eggs’ coverings split, escaping spores are picked up by passing air currents and carried aloft to settle and possibly germinate further afield (Dickinson and Lucas 1979; Hassett et al., 2013).
Habits and Habitat Bird’s nest fungi grow alone, in clusters
or crowded colonies on wood, dung, mulch, manured soil, and plant-based detritus in moist and shaded locations or open areas. Teir mycelial cords or rhizomorphs quickly invade substrates and aggressively travel through soil. BNF are also geotropic, i.e. they use their sense of gravity to tilt their cup openings upward to catch the waterdrops essential for spore dispersal. Wild habitats include surfaces along the margins of tree canopy openings where raindrops and water drips from leaves can easily strike the
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