Frozen buds

close-up, the flower buds of the weed Arabidopsis thaliana appear almost animal-like. The scanning electron micrographs above show a whole inflorescence (top right) and two individual flower buds in detail. The bud of a Columbia wild-type plant shown at bottom right has an oval shape and is tightly closed — as buds normally remain until the anther matures inside. By contrast, the bud on the left is short and fat, and the pistil protrudes through the anther, petal and sepal whorls, even though the bud is at a very early stage. These flower bud abnormalities are characteristic of plants in which the erh3 gene is mutated. Plants with the erh3 mutation were isolated because they show an abnormal pattern of root hairs. The fact that the leaf trichomes and flowers are also affected in the mutants indicates that the gene is involved in several different aspects of the development of the whole plant, presumably by means of interactions with a variety of different factors. The pictures reflect the highly organized state of the surface of a plant organ. The outer cell wall structure and shape are clearly visible, and epicuticular deposits can be seen on most of the epidermis cells and on the spike-like trichomes of the buds. These deposits, which probably consist of wax, form a mesh covering the outer surface of the cells. This is visible as spots or bumps on the trichomes, and as ripples on the surface of most of the other epidermal cells. These images were obtained by cryo scanning electron microscopy. Because it is quick and excludes any chemical treatments, this technique provides good images of specimens in their native state.