Pattern of pore morphogenesis in the resupinate basidiome of Phellinus contiguus

On malt agar in Petri dishes in the light, basidiome development of the resupinate polypore Phellinus contiguus proceeded centrifugally after a minimum but variable colony diameter had been attained. Dissepiments were initiated as more or less separate islands of aerial hyphae approximately 3 mm behind the mostly submerged mycelial margin. Localized aerial fascicles of apically-extending hyphae grew from these island initials both horizontally, where they coalesced with fascicles from adjacent initials and delimited pores, and vertically, resulting in lengthening of dissepiments. On dilute (0.2%) malt agar and towards the edge of dishes containing more concentrated malt agar, initials tended to fail to unite laterally and grow as vertical spines. Horizontal growth of branching and interconnecting aerial fascicles also occurred at the margins of more mature poroid basidiome patches, increasing the poroid area. Time lapse studies of development from widely spaced initials transferred to fresh medium weekly showed that on 0.2% malt agar, areas with basidia and lacking extending aerial hyphae remained as the bases of developing primary tubes. On 2 % malt agar secondary tubes were formed at a later stage by differential vertical growth within dissepiment areas. Where groups of initials were removed poroid basidiome tissue was regenerated mainly by lateral fascicle development from the surrounding basidiome tissue.