Introduction to Fungi, Third Edition

AURICULARIALES
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Fig 21.7 Life cycle of Auricularia auricula-judae. Depending on the substrate, a basidiospore has various options by which to
germinate; these are equivalent for both mating types, but for clarity we show them here for only one of them (white nuclei).
Basidiospores falling onto the fruit body hymenium may germinate by repetition to form another ballistospore. Depending on the
nutrient status, basidiospores may germinate by formation of a monokaryotic mycelium or by producing lunate microconidia.The
latter may also be produced by monokaryotic hyphae.Conjugation leads to the establishment of a dikaryotic mycelium which may
form basidiocarps. Key events in the life cycle are plasmogamy (P), karyogamy (K) and meiosis (M). Haploid nuclei are drawn as
empty or filled circles; the diploid nucleus is drawn larger and half-filled.
21.4.2 Other members of the
Auriculariales
Exidia
Exidia glandulosa, sometimes called ‘witches’
butter’, forms black rubbery fructifications on
decaying branches of various woody hosts, especially
lime (Tilia) and oak (Quercus) (Fig. 21.9a).
The hymenium is borne on the lower side of the
fruit body and in this species is studded with
small black warty outgrowths. The basidia are
formed deep within the hymenium and produce
long epibasidia. They are divided by longitudinal
instead of transverse septa (Fig. 21.8).
Basidiospores of E. glandulosa show germination
patterns identical to those described above
for A. auricula-judae, and Ingold (1982b) found
that the only clear microscopic difference
between these two species is the arrangement
of septa in the basidium. Phylogenetic studies
have confirmed the close relationship between
Auricularia and Exidia (Weiss & Oberwinkler, 2001).
Pseudohydnum gelatinosum
This species grows on dead stumps and branches
of coniferous trees. The fruit body is jelly-like in
consistency and has a short eccentric stalk.
The hymenium is on the lower side of the
pileus and is arranged into numerous conical
teeth (Fig. 21.9b) resembling those of Hydnum.
The basidia are similar to those of Exidia in
being longitudinally septate. As in Exidia and
Auricularia, basidiospores failing to escape from