Development and growth of the lichen Rhizocarpon geographicum

Richard A. Armstrong, S.N. Smith

Research output: Contribution to journalArticle

Abstract

The development of new areolae on the marginal hypothallus of the lichen Rhizocarpon geographicum (L.) DC was studied after complete or partial removal of the central areolae. New areolae developed slowly on the isolated hypothalli over two years. Development was similar when the areolae were completely removed and when the central areolae were separated from the marginal hypothallus by ‘moats’ 2 to 5 mm in width. However, in intact thalli, the marginal areolae developed rapidly during Jan. – June 1986 but showed periods of retreat from the margin during Oct. - Dec. 1985 and July – Sept. 1986. These results suggested that primary areolae may develop from free-living algal cells trapped by the hypothallus while secondary areolae may develop from zoospores produced by the thallus. Complete removal of the areolae resulted in no measurable radial growth of the marginal hypothallus over 18 months. Removal of the central areolae to within 1 and 2 mm of the hypothallus significantly reduced growth. These results suggest that the areolae may supply the hypothallus with carbon for growth. When the marginal hypothallus was experimentally removed a new hypothallus developed within one year. Regeneration occurred initially by retreat of the marginal areolae and later by new hyphal growth. The concentration of ribitol, arabitol and mannitol was measured in the areolae and marginal hypothallus on four occasions in 1985/6 in a population growing on a steep south facing rock surface. The three carbohydrates were present in significantly higher concentration in the areolae than in the hypothallus. Hence, the slow growth of this species may result from inhibited transport of carbohydrate from areolae to hypothallus.
Original languageEnglish
Pages (from-to)287-300
Number of pages14
JournalSymbiosis
Volume3
Issue number3
Publication statusPublished - 1987

Fingerprint

Rhizocarpon
Lichens
Nipples
Growth and Development
thallus
lichens
growth and development
carbohydrates
zoospores
mannitol
rocks
carbon
cells
Growth
Ribitol
Carbohydrates

Keywords

  • rhizocarpon geographicum
  • carbohydrates
  • gas chromatography
  • hypothallus
  • areolae

Cite this

Armstrong, R. A., & Smith, S. N. (1987). Development and growth of the lichen Rhizocarpon geographicum. Symbiosis, 3(3), 287-300.
Armstrong, Richard A. ; Smith, S.N. / Development and growth of the lichen Rhizocarpon geographicum. In: Symbiosis. 1987 ; Vol. 3, No. 3. pp. 287-300.
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Armstrong, RA & Smith, SN 1987, 'Development and growth of the lichen Rhizocarpon geographicum', Symbiosis, vol. 3, no. 3, pp. 287-300.

Development and growth of the lichen Rhizocarpon geographicum. / Armstrong, Richard A.; Smith, S.N.

In: Symbiosis, Vol. 3, No. 3, 1987, p. 287-300.

Research output: Contribution to journalArticle

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