Introduction to Fungi, Third Edition

584 HOMOBASIDIOMYCETES: GASTEROMYCETES
Fig 20.4 Cyathus stercoreus. (a) Section of immature gasterocarp showing peridioles. (b) Gasterocarp cut open and pinned back to
show the attachment of the peridioles. (c e) Details of structure of funiculus. (c) Condition of funiculus before stretching.
(d) Stretched funiculus.Note the funicular cord within the purse. (e) Funicular cord extended after rupture of the purse.The base of
the funicular cord is frayed out to form the hapteron. (f) Portion of funicular cord. Note the spirally coiled hyphae.The thickenings
are modified clamp connections. (g) Detail of peridiole wall and contents (b, basidiospore; c, cortex; e, epiphragm; em,
emplacement;f,funiculus;f.c.,funicularcord;h,hapteron;m.c.,mylialcords;m.p.,middlepiece;p,peridiole;pu,purse;s,sheath;
t, tunica).
The gasterocarps of Cyathus and Crucibulum
have been aptly termed splash cups because the
peridioles are splashed out by the action of rain
drops to distances of over 1 m. The key to
understanding the mechanism of discharge lies
in the structure of the funiculus. In Cyathus
(Figs. 20.4d,e), the funiculus is made up of several
characteristic structures (see Brodie, 1975).
The sheath is a tubular network of hyphae
attached to the inner surface of the gasterocarp.
It terminates in the middle piece where the
innermost hyphae of the sheath unite to form a
short cord. The middle piece flares out at its top
where its hyphae are attached to a cylindrical sac,
the purse, which is firmly attached to the
peridiole at a small depression. Folded up
within the purse is a long strand of spirally
coiled hyphae, the funicular cord (Fig. 20.4f). The
free end of the funicular cord is composed of a
tangled mass of adhesive hyphae, the hapteron.
Rain drops, which may be as much as 4 mm in
diameter and have a terminal velocity of about
8ms 1 , fall into the cup. Drops of this size
are most likely to drip from the woodland
canopy (Savile & Hayhoe, 1978). The force creates
a strong upward thrust which tears open the