Quote:
'Vessel elements are the building blocks of vessels, which constitute the major part of the water transporting system in the plants where they occur. Vessels form an efficient system for transporting water (including necessary minerals) from the root to the leaves and other parts of the plant.
In secondary xylem, a vessel element originates from a fusiform initial in the cambium, at maturity the protoplast dies and disappears, but the lignified cell walls persist. It may be seen as a dead cell, which still has a function, and is still being protected by surrounding living cells.
The cell wall is strongly lignified. At both ends there are openings that connect the individual vessel elements. These are called perforations or perforation plates. These perforations may have a variety of shapes: the most common are the simple perforation (a simple opening) and the scalariform perforation (several elongated openings on top of each other in a ladder-like design). Other types include the foraminate perforation plate (several round openings) and reticulate perforation plate (net-like pattern, with many openings). The side walls will have pits, and may have spiral thickenings.'
http://en.wikipedia.org/wiki/Vessel_element
Saccalabium is a Genus of Tropical orchids, Charles Darwin was interested in the arrangement of the spiral vessel elements in the developing flower of the Orchid, and discussed the current theory of the time that the organisation of these vessels might help shed light on the homologies between the parts of flowers of different plant families. http://www.darwinproject.ac.uk/entry-5097
This slide was imaged with a Nikon Diaphot microscope, using a LWD 0.55 phase/DIC condener and X20 0.40 Plan DIC objective. The method of illumination was polarisation produced by dialing the upper and lower Wollaston prisms out of the light path, but retaining the upper polariser, moveable 1/4 wave plate and lower analyser. In addition the Ph2 phase annulus was included in the light path to provide an element of oblique lighting to the rather 'flat' polar image. The camera was a Canon 40D mounted in the front SLR port and total magnification was X50.
The image is formed by stitching the outputs of two image stacks, using Microsoft ICE. In total 25 images were collected.

A larger version of the image is located here. http://photosynth.net/view.aspx?cid=77a ... c729836faf
The background was set to black in Photoshop.
Original red background. Stacking with Zerene DMap

The structure of the spiral bundles of birefringent fibrils in the wall of the vessel is fascinating. If you try to follow it in 3D, it reminds me very much of a Moebius strip
