The water relations, stomatal conductance, size, chlorophyll and proline content have been measured in sun and shade leaves of four evergreen sclerophyll species, throuthout the year. It was found that there were no major differences in water status of the two leaf types. However, in young expanding shade leaves, higher stomatal conductance, turgor, chlorophyll and proline content leves was significantly larger. Plastochron ratios of the two leaf types in the four species were similar, indicating a synchronized gorwth rate related to seasonal rhythemicity. It is suggested that different mechanisms have been operating in the response of the two leaf-types to microclimatic conditions: an avoidance by sun leaves and tolerance by shade leaves.

Leaf water relationships were studied in eleven evergreen sclerophyll species from a macchia near Athens, Greece. Water (ψ), solute (ψ_s) and turgor (ψ_p) potentials as well as relative water content (RWC) and stomatal conductance were measured during the course of a year. Relatively high values of water potential were measured initially in the young expanding leaves during the 60–90 d of the growth period. After this period a soil moisture deficit developed and leaves increased to full size. During the drought period leaf water potential and solute potential values, as well as stomatal conductance were low. The results show that during the dry season (Jun.–Aug.) all species are at or near zero turgor and this occurs in Arbutus, Myrtus and Nerium at around −1.5 MPa, in Ceratonia, Pistacia and Quercus at around −2.0 MPa, in Laurus, Olea and Phillyrea below −3·5 MPa. These values largely reflect differences in ψ_s at this time. Also, the seasonal variations in the water relations components reflect the responses of the different species to variation in water availability.

Capparis spinosa (caper), a winter‐deciduous perennial shrub, is a consistent floristic element of Mediterranean ecosystems, growing from May to October, i.e. entirely during the prolonged summer drought. The internal architecture of young and fully expanded leaves was studied, along with certain physiological characteristics. Capparis spinosa possesses thick, amphistomatic and homobaric leaves with a multilayered mesophyll. The latter possesses an increased number of photosynthesizing cells per unit leaf surface, a large surface area of mesophyll cells facing intercellular spaces (S_mes) and a low percentage of intercellular space per tissue volume. S_mes and chlorophyll content attain their maximum values synchronously, slightly before full leaf expansion. Nitrogen investment is also completed before full leaf expansion. The structural features, in combination with the water status, could contribute to enhanced rates of transpiration and photosynthesis under field water shortage conditions.