2024-03-28T18:08:51Zhttp://digital.csic.es/dspace-oai/requestoai:digital.csic.es:10261/207892019-08-06T09:52:14Zcom_10261_50com_10261_8col_10261_303
Water Distribution in Foliose Lichen Species: Interactions between Method of Hydratation, Lichen Substances and Thallus Anatomy
Souza-Egipsy, Virginia
Valladares Ros, Fernando
Ascaso, Carmen
Lichen
Water relations
Semi-arid
Lichen substances
LTSEM
Thallus anatomy
Extracellular water
Neofuscelia pokornyi (Körb.) Essl
Neofuscelia pulla (Ach.) Essl
Xanthoria parietina (L.) Th. Fr.
6 pages, figures, and tables statistics.
Three lichens (Neofuscelia pokornyi, N. pulla and Xanthoria parietina) from a semi-arid habitat were examined using
low-temperature scanning electron microscopy to evaluate the e ects of hydration method, lichen substances and
thallus anatomy on the water distribution of hydrated thalli. In the Neofuscelia species, extracellular water within the
thallus was observed in association with cracks in its otherwise impervious upper cortex, while X. parietina showed
abundant extracellular water between medullary hyphae. Spraying the thalli followed by maintenance for 14±20 h in
a water-saturated atmosphere led to the disappearance of the external water ®lm in X. parietina but not in the
Neofuscelia species. Surface water was abundant in specimens of all species immediately after spraying for 15 min. No
extracellular water was observed inside the thallus 14±20 h after spraying, but after rinsing with acetone its presence
was detected in all three species. Hydric strategy correlated with cortex hygroscopicity: X. parietina, an aero-
hygrophytic species, had a more hygroscopic upper cortex than the Neofuscelia species, which are substrate-
hygrophytic. The hygroscopicity of the upper cortex was linked with the amount of extracellular water in the thalline
interior. Di erences between X. parietina and Neofuscelia in the polarity and distribution of their lichen substances
agreed with species di erences in the presence and distribution of free water both as a ®lm over the surface and inside
the thallus. Lichen substances appear to play a role in the maintenance of air-®lled intrathalline spaces in species
whose anatomy, habitat, or both, favour water-logged conditions.
Peer reviewed
2010-02-08T09:24:08Z
2010-02-08T09:24:08Z
2000
artículo
http://purl.org/coar/resource_type/c_6501
Annals of Botany 86: 595-601 (2000)
0305-7364
http://hdl.handle.net/10261/20789
10.1006/anbo.2000.1224
en
http://dx.doi.org/10.1006/anbo.2000.1224
open
1548393 bytes
application/pdf