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Primary xylem
Oak wood
Leaf vein
Vein ends
Bean seed
Pine tracheids, xs
Fern TE, xs
Fern, TE, mag
Annular walls
Annular, stretched
Annular, narrow
Scalariform walls
Scalar., narrow
CBP, pine
CBP, dicot
CBP, irregular
Contact faces
Pits, side view
CBP, pine, xs
CBP,angio, xs
CBP, fern, xs
Contact face, xs
Simple perf. plate 1
Simple perf. plate 2
Pitted perf. plate
Perf. plate & helix
Perf. plate, face
Perf. plate, mag
Perf. plate, section
Perf. plate rim
Perf. plate & wall
Scalariform Per plate
Primary xylem
Vessel sizes
Fern TE
Pine needle
VE precursor, ls
Protoxylem
9 Contact faces
VE precursor, xs
Precursor 2
Torn vessel
Torn vessel 2

Fig. 7.5-3. Transverse section of a vessel element in muskmellon (Cucumis). This vessel element is so much larger than all surrounding cells that it has 9 contact faces in this section alone (the surrounding cells are probably shorter than the vessel element, so if we could see the entire surface, there might be more than 20 contact faces). However, when this vessel element was first formed, is was just a small parenchyma cell about the same size as surrounding cells and probably with only about five or six contact faces (if all cells are about the same size, a transverse section would show about six contact faces – like a honeycomb). As it enlarged, it pushed the surrounding cells apart and formed new contacts with cells that had originally not been next to it. Despite the fact that these cell-cell contacts were made by cells pushing up against each other (rather than being formed by a cell plate during cell division), they still are able to form pit-pairs.