Differences in stomatal number per unit area within the same species under different micro-environmental conditions: A working hypothesis

Abstract

A summary of Salisbury's (1927) work on stomata is presented here. He found, basically, that the number of stomata per unit area increased under more xerophytic conditions. This is contrary to prevalent opinion, that postulates that under more humid conditions, the number of stomata can be greater, as there is less danger of dehydration. A hypothesis is presented here that can explain this: The more xerophytic the conditions, the higher the number of stomata per unit area to permit more efficient gas interchange at those times when relative humidity is high, and danger of excessive dehydration is lowest.

Leaf morphology of 89 tree species from a lowland tropical rain forest (Atlantic forest) in South Brazil

“…All species possessed hypostomatic leaves (Figs. 3a, 3b), which could be related to the relative humidity (higher at the abaxial surface than at the adaxial surface) and to temperature (higher at the adaxial surface than abaxial surface) of leaves at the canopy of the forest (Lleras, 1977). Also, the presence of stomata in the abaxial surface could represent a way to prevent the obliteration of the pores of stomata by epyphyllous organisms (Coutinho, 1962).…”

Comparação da morfologia foliar de espécies arbóreas de três estádios sucessionais distintos de floresta ombrófila densa (Floresta Atlântica) no Sul do Brasil

“…As densidades estomáticas mais altas do estádio inicial são relacionadas às condições xéricas, pois quanto maior a freqüência estomática por unidade de área, maior a eficiência de trocas gasosas no período em que os estômatos estão abertos, devido às condições mais favoráveis do ambiente (Lleras 1977). Entretanto, a densidade estomática está também relacionada com o tamanho, posição e controle de abertura dos estômatos (Kozlowski & Pallardy 1997), o que afeta a absorção de CO 2 .…”

“…Essas formam o padrão mais comum de distribuição de estômatos para plantas terrestres, o que representa uma proteção contra as condições microambientais, tais como a temperatura mais elevada na face adaxial (devido à intensa exposição solar quando se tratam de folhas de sol do dossel) (Lleras 1977) e o grau de umidade (que na face abaxial é maior quando comparada com a face adaxial) (Smith & McClean 1989).…”

Morpho-anatomical and micromorphometrical evaluations in soybean genotypes during water stress

“…The drought effects on leaf area and abscission could be a reflection of leaf-nutrient deficiencies. Reduction in leaf area constituted a defense strategy to minimize the water loss (Begg and Turner, 1976;Lawlor, 1993;Mansfield and Davies, 1985) and could be viewed as a xeromorphic characteristic (Brüning, 1973); Lleras, 1977 andTurner, 1994). According to Boeger and Wisniewski (2002), leaf area is regulated by the balance between the carbon gain and water lost.…”