Conventional and analytical electron microscopy (EDX, ESI, EELS) were used to investigate the silicon accumulation, the chemical nature of the Si deposits and their formation in three species of monocotyledons. In Deschampsia , in particular parts of the outer epidermal cell wall silicon is accumulated as silicic acid. Electron dense, needle‐shaped crystals in the vacuoles of epidermal cells and in the intercellular spaces were also identified as silicic acid. In xylem parenchyma cells, silicon is accumulated as SiO2, which is formed from Sn silicate. In Festuca , crystal‐like deposits of SiO2 occur on the epidermal surface, in the epidermal and parenchyma cell walls, and in vacuoles of bundle sheath cells. Often the deposits disturb the cell walls and penetrate the envelope of plastids and mitochondria. The crystal‐like SiO2 deposits originate from Sn silicate. In the pericarp of ripe nuts of Schoenus , no stainable cell wall components are detected. The inner part of the pericarp consists of silicic acid, while in the outer regions small clusters of silicic acid are embedded in a matrix of SiO2. The silicic acid deposits show an unusual, layered structure, typical for lepidoic silicic acids, which consist of two‐dimensional crystals lying one above the other.

Treatment of barley leaf segments with jasmonic acid methyl ester (JM) leads to the accumulation of a set of newly formed abundant proteins. Among them, the most abun dant protein exhibits a molecular mass of 23 kDa (JIP‐23). Here, data are presented on the occurrence and expression of the lIP‐23 genes in different cultivars of Hordeum vulgare . Southern blot analysis of 80 cultivars revealed the occurrence of 2 to 4 genes coding for JIP‐23 in all cultivars. By means of Northern blot and immunoblot analysis it is shown that some cultivars lack the ex pression of jip‐23 upon treatment of primary leaves with JM as well as upon stress performed by incubation with 1 M sorbitol solution. During germination, however, all tested cultivars ex hibited developmental expression of jip‐23 . The results are dis cussed in terms of possible functions of JIP‐23 in barley.