• Lavender leaf

    Date:14 August 2012 Tags:, , ,

    Annie Cavanagh and David McCarthy

    This false-coloured scanning electron micrograph (SEM) shows a lavender leaf (Lavandula), imaged at 200 microns. Lavender yields an essential oil with sweet overtones, which can be used in balms, salves, perfumes, cosmetics and topical applications. It is also used to aid sleep, to relax and to alleviate anxiety. The surface of the leaf is covered with fine hair-like outgrowths made from specialised epidermal cells called non-glandular trichomes, which protect the plant against pests and reduce evaporation from the leaf. Glandular trichomes are also present, containing the oil produced by the plant.

    What are the spiky structures on the leaf surface?
    The surface of the leaf is densely covered with fine hair-like outgrowths made from specialised epidermal cells called non-glandular trichomes, which are found on a wide variety of plant species. The hairs keep frost away from the surface cells and break up the flow of air across the leaf surface, reducing evaporation. Dense coatings of trichomes also reflect solar radiation, protecting the delicate tissue beneath. In habitats where plants rely on their supply of water from cloud drip, trichomes have been found to enhance this collection process. In addition, trichomes protect the plant against pests because the hairs interfere with their feeding process. Glandular trichomes, which contain volatile oils and other secretions that are produced by the plants, are also present on the surface of the leaf.

    Why did the judges like this image?
    Alice Roberts (anatomist, author and TV presenter) explains: “This gorgeous, extreme close-up of the surface of a lavender leaf, viewed through a scanning electron microscope, clearly shows the bulging droplets of oil that provide the plant with its heady scent. Artificial colour has been used brilliantly here, to pick out the salient details, but also gives the image a startling Avatar-like quality.”

    The 12th Wellcome Image Awards were announced on 20 June 2012, recognising the creators of the most informative, striking and technically excellent images among recent acquisitions to Wellcome Images, as chosen by a panel of judges.



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