Higher Plants - Leaves and Petals
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Rock cress (Arabidopsis)
Cryo-fixed rock cress (Arabidopsis) leaf: trichome with virus. 3kV, secondary electron image. Second picture is higher power: 2.5kV, secondary electron image. Uncoated.
Images courtesy of FEI and the Max Planck Institute, Cologne, Germany.
Lavender leaf
Shows branching trichrome structures (blue) which help to protect the plant from predation. On the surface of the leaf are well preserved stomata (with their typical sausage shaped guard cells) through which gaseous exchange occurs. Characteristic lavender oil droplets (red) can be seen on the leaf surface.
English lavender (Lavandula angustifolia)
Cryo-SEM prepared cross-section of English lavender (Lavandula angustifolia), showing trichomes. These help to trap a layer of air around the leaf to reduce transpiration, or water loss. The specimen was rapidly frozen, cold fractured, sublimated and coated prior to examination on a JEOL JSM-6490 SEM (original magnification: x500).
Image courtesy of the Imaging and Cytometry Laboratory at the University of York, England.
http://www.york.ac.uk/depts/biol/tf/imaging-cytometry/ic_electron.htm
Cryo-DualBeam prepared petal from a tobacco plant flower
SEM (secondary electron) image of an ion beam milled cross-section through a cryogenically-prepared petal from a tobacco plant flower. Note that it is not possible to achieve such precision using conventional fracturing techniques. Image taken using PP2000T attached to an FEI Quanta 3D 200 DualBeam.
Image courtesy of FEI Company, UK.
Plant leaf spongy mesophyl
Bar: 10um (inset: 5um)
Pesticide droplets on the surface of Taraxcum sp leaf
Droplets in the size range 5-10um were sprayed onto the upper surface of the leaf. The epidermis bears waxes so the droplets, in many cases, run off in to the clefts between epidermal cells. Conventional preparation methods would clearly not be suitable for demonstrating this unusual distribution.
Bar: 50um (inset: 25um)
Epicuticular waxes on the adaxial surface of the ‘wax plant’ (Hoya carnosa)
These waxes are very delicate and damage can easily occur during conventional processing for SEM. Hoya carnosa has a cutinised/suberised cuticle some 10-15um in thickness (marked by arrows) with a delicate array of waxes on the outer surface. These are easily demonstrated using low-temperature SEM.
Pectic strands
The cellulose walls of the contiguous parenchyma cells are cemented together with a thin layer of pectin. As the cells expand and differentiate, they become more spherical and the area of cell contact diminishes. Intercellular spaces are created and the pectin is drawn out in the form of gummy strands.
These structures are tenuous and break readily during conventional processing for electron microscopy. Only as a result of the development of low-temperature SEM have these structures been fully characterised.
Leaf of Euphorbia myrsinites (Donkey-tail or Myrtle spurge)
Note the wax-producing cells and wax on the leaf surface (wax is not retained during critical point drying). The specimen was prepared on a JEOL JSM-6490 fitted with a PP2000.
Images courtesy of Meg Stark at the Department of Biology, University of York, England.
http://www.york.ac.uk/depts/biol/tf/imaging-cytometry/ic_electron.htm