Mesophyll structure during leaf development in Ballota acetabulosa

Abstract

SUMMARYMesophyll structure and water relations were studied in expanding and expanded dorsiventral leaves of Ballota acetabulosa Benth., a wild perennial sbrub from tbe Mediterranean. The spongy mesophyli was developed earlier than tbe palisade in expanding leaves and exhibited a larger internal exposed surface. By contrast, in fully expanded leaves tbe internal exposed surface was much larger in the palisade tban in spongy mesophyll, Tbe development of chloroplasts in cells of both mesophyll tissues, as well as their arrangement along tbe cell walls exposed to intercellular canals, coincided with the formation of intercellular spaces. Leaf expansion appears to be positively related to increasing internal exposed surface and declining water potentials. As a result, mature leaves possess a higb ratio of internal exposed surface per leaf area and low values of turgor. It is considered that an increase in the internal exposed surface migbt be an adaptive feature for small-leaved shrubs, grown under water deficiency.

Development and Structure of Drought-tolerant Leaves of the Mediterranean Shrub Capparis spinosa L.

“…The number of mesophyll cells per unit of leaf surface in C. spinosa is high. For example, it is six-fold higher than that of the xerophyte Ballota acetabulosa L. (Psaras and Rhizopoulou, 1995). This can be attributed to (a) the small cell diameter (15±20 mm), (b) the leaf thickness and (c) the tight arrangement of cylindrical photosynthetic cells in both the adaxial and the abaxial mesophyll.…”

“…Intercellular air space (ICS) and the mesophyll cell surface exposed to internal leaf atmosphere (S mes ) were measured using the methods of Parkhurst (1982). Some of the measurements were con®rmed using the method of Turrell (1936) (see also Psaras and Rhizopoulou, 1995). Stomatal density was determined on both adaxial and abaxial surface, from paradermal sections and from leaf imprints made with a dental material (Sandro-sil preci¯ow, Cologne, Germany); data presented are derived from ®ve leaves, ten replicates for each leaf surface at each developmental stage.…”

Leaf and green stem anatomy of the drought deciduous Mediterranean shrub Calicotome villosa (Poiret) Link. (Leguminosae)

“…The low CO 2 uptake rate found in some green-stemmed xerophytes was attributed to the high touching degree of the cells, resulting in less free cell wall area for CO 2 diffusion. On the contrary, chlorenchyma cells of the C. villosa stem are well separated from each other, possessing all typical features of palisade cells as these have been widely accepted (Evans and Loretto, 2000;Fahn and Cutler, 1992;Psaras and Rhizopoulou, 1995): being cylindrical, they touch each other along a line, forming triangular intercellular spaces. After comparing paradermal sections of C. villosa stem chlorenchyma to similar sections of the leaf palisade chlorenchyma, it is concluded that they are very similar (cf.…”

A study on functional and structural traits of the nocturnal flowers of Capparis spinosa L.

“…The tissue was post-fixed in 1% osmium tetroxide for 2 h at 4 1C, dehydrated in a graded ethanol series embedded in Durcupan ACM (Fluka) and incubated at 60 1C for 24 h. Semithin sections were cut on an LKB Ultratome III and observed with a ZEISS light microscope (Christodoulakis, 1989). Intercellular space (ICS) was investigated on 51 petal cross-sections taken from 10 different petals (Psaras and Rhizopoulou, 1995); the area of ICS, as it appeared in the micrographs, was traced and blackened on a transparent overlay and measured with a Delta-T area meter. Scanning electron microscopic (SEM) observations of epidermis in sepals and petals were prepared according to a method described by Levizou et al (2002).…”