Elsevier

Mycological Research

Volume 96, Issue 12, December 1992, Pages 1033-1043
Mycological Research

Conidiogenesis in five species of Umbilicaria

https://doi.org/10.1016/S0953-7562(09)80113-5Get rights and content

The ultrastructure of thalloconidium development in the lichen-forming fungi Umbilicaria aprina, U. decussata, U. havaasii, U. polyphylla and U. vellea was studied and compared. The thalloconidia are formed directly from the scleroplectenchymatous tissues of the lower cortex or from rhizinomorphs protruding from the lower cortex of the thalli. Conidiophores and conidiomata are absent. The thalloconidia of the five species differ in size, septation, and cytology but their genesis is similar with regard to the differentiation of wall-layers and pigmentation. Free vegetative hyphae in the medulla and fused hyphae in the lower cortex have three distinct wall layers; the thalloconidia emerge from the lower cortex with two wall-layers, usually having shed the outermost, amorphous third wall-layer. Thalloconidium formation is accompanied by a number of changes in cytology and cell wall features. The basic determinant on size and number of cells appears to be the architectural constraints associated with the site of production.

References (24)

  • HawksworthD.L.

    A revision of lichenicolous fungi accepted by Keissler in Coniothecium

    Transactions of the British Mycological Society

    (1975)
  • HessW.M.

    Fungal organelles and other cell structures

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