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Diffuse growth in the fruticose beard lichen Ramalina usnea (L.) R. Howe

  • William B. SANDERS (a1) and Sherzod A. TOKAMOV (a1)
Abstract

Very little is known about how growth is distributed within thalli of fruticose lichens. To determine whether mature, non-apical regions of the beard lichen Ramalina usnea elongate, segments of the broadest axes were marked with thread and measured; thalli were then returned to the field to resume growth for about one year. Growth was evident in all segments measured and increments were roughly proportional to length, suggesting that elongation occurs throughout the thallus. New thallus axes (branches) were organized from buds that emerged from mature tissue, usually along pseudocyphellae and surfaces exposed by breakage. Axes were very fine at their extremities and possessed an inrolled apex from the time of bud emergence. No evidence of apical branching was observed. The thallus cortex consisted of very thick-walled fungal cells oriented longitudinally. In transverse section, cells gave the appearance of being grouped within fascicles, indicating that branch cells grow within the older cell wall material of their neighbours, as occurs in the cortex of Ramalina menziesii and the medullary cord of Usnea longissima. A continued accumulation of cell wall layers may be related to the mature tissue's capacity to sustain elongation growth.

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Anglesea, D., Greenhalgh, G. N. & Veltkamp, C. J. (1983) The structure of the thallus tip in Usnea subfloridana . Lichenologist 15: 8188.
Armstrong, R. A. & Smith, S. N. (1998) Does radial growth of the lichen Parmelia conspersa depend exclusively on growth processes at the lobe tip? Environmental and Experimental Botany 39: 263269.
Boissière, M.-C. (1979) Cytologie du Peltigera canina en microscopie électronique: le micobionte à l'état végétatif. Révue de Micologie 43: 170.
Boucher, V. L. & Nash, T. H. III (1990) Growth patterns in Ramalina menziesii in California: coastal vs. inland populations. Bryologist 93: 295302.
Brodo, I. M., Sharnoff, S. D. & Sharnoff, S. (2001) Lichens of North America. New Haven & London: Yale University Press.
Cramer, C. (1891) Über das Verhaeltniss von Chlorodictyon foliosum J. Ag. (Caulerpeen) und Ramalina reticulata (Noehden) Krplhb. (Lichenen). Berichte der Schweizerischen botanischen Gesellschaft 1: 100123.
Fisher, P. J. & Proctor, M. C. F. (1978) Observations on a season's growth in Parmelia caperata and P. sulcata in South Devon. Lichenologist 10: 8189.
Greenhalgh, G. N. & Anglesea, D. (1979) The distribution of algal cells in lichen thalli. Lichenologist 11: 283292.
Hale, M. E. (1970) Single-lobe growth-rate patterns in the lichen Parmelia caperata . Bryologist 73: 7281.
Hale, M. E. (1979) How to Know the Lichens, 2nd edn. Dubuque, Iowa: William C. Brown.
Henssen, A. & Dobelmann, A. (1987) Development of the spongiostratum in Anzia and Pannoparmelia . Bibliotheca Lichenologica 25: 103108.
Herre, A. C. (1904) The growth of Ramalina reticulata . Botanical Gazette 38: 218219.
Hill, D. J. (1994) The cell cycle of the photobiont of the lichen Parmelia sulcata (Lecanorales, Ascomycotina) during development of the thallus lobes. Cryptogamic Botany 4: 270273.
Honegger, R. (2008) Morphogenesis. In Lichen Biology, 2nd Edition (Nash, T. H. III, ed.): 6993. Cambridge: Cambridge University Press.
Jansson, K. U., Palmqvist, K. & Esseen, P.-A. (2009) Growth of the old forest lichen Usnea longissima at forest edges. Lichenologist 41: 663672.
Kashiwadani, H. (1990) Some Chilean species of the genus Ramalina (lichens). Bulletin of the National Science Museum, Tokyo, Series B 16 (1): 112.
Kashiwadani, H. & Nash, T. H. III (2004) Ramalina. In Lichen Flora of the Greater Sonoran Desert Region, Vol. 2 (Nash, T. H. III, Ryan, B. D., Diederich, P., Gries, C. & Bungartz, F., eds): 440455. Tempe, Arizona: Lichens Unlimited, Arizona State University.
Keon, D. B. & Muir, P. S. (2002) Growth of Usnea longissima across a variety of habitats in the Oregon Coast Range. Bryologist 105: 233242.
Larson, D. W. (1983) Morphological variation and development in Ramalina menziesii Tayl. American Journal of Botany 70: 668681.
Lutz, K. G. (1894) Ueber die sogenannte Netzbildung bei Ramalina reticulata Krplhbr. Berichte der Deutschen Botanischen Gesellschaft 12: 207214.
Peirce, G. J. (1898) On the mode of dissemination and on the reticulations of Ramalina reticulata . Botanical Gazette 25: 404417.
Rolstad, J. & Rolstad, E. (2008) Intercalary growth causes geometric length expansion in Methuselah's beard lichen (Usnea longissima). Botany 86: 12241232.
Rundel, P. (1978) Evolutionary relationships in the Ramalina usnea complex. Lichenologist 10: 141156.
Sanders, W. B. (1989) Growth and development of the reticulate thallus in the lichen Ramalina menziesii . American Journal of Botany 76: 666678.
Sanders, W. B. (1992) Comparative in situ studies of thallus net development in morphologically distinct populations of the lichen Ramalina menziesii . Bryologist 95: 192204.
Sanders, W. B. (1993) Apical formation of cilia and associated branching of the axis in the lichen Teloschistes flavicans . International Journal of Plant Sciences 154: 7579.
Sanders, W. B. & Ascaso, C. (1995) Reiterative production and deformation of cell walls in expanding thallus nets of the lichen Ramalina menziesii (Lecanorales, Ascomycetes). American Journal of Botany 82: 13581366.
Sanders, W. B. & de los Ríos, A. (2012) Development of thallus axes in Usnea longissima (Parmeliaceae, Ascomycotina), a fruticose lichen showing diffuse growth. American Journal of Botany 99: 9981009.
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The Lichenologist
  • ISSN: 0024-2829
  • EISSN: 1096-1135
  • URL: /core/journals/lichenologist
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