Virtual Museum of Canada
Jardin botanique de Montréal 
Centre for Forest Research

Transcription of video clip Division of labour

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In their sapwood, leafy trees, much like plumbers, join narrow pipes together to create long conduits.

Schematic of a vessel with a partially disappearing end wall

© Jardin botanique de Montréal
Vessel elements

They construct their vessels, which run several meters – the entire height of the tree – by connecting vessel members that are barely several millimeters long.

Only a small edge remains where end walls initially separated the two vessel elements.

This perforated end wall is said to be "single", since the opening is large and circular.

This multiple perforation of the end wall is ladder-like, or scalariform, in shape.
Whereas this one, like a net, is reticulated.

Schematic of interconnected vessels

© Jardin botanique de Montréal
Interconnexions between vessels

The vessels engage in exchange with neighboring cells of different levels of the tree through perforations.

The vessels are also linked to each other through these perforations.

In this way, water is channeled from the same source up through different routes.

This allows the xylem to continue to function even if certain avenues are blocked. A little like detours during road construction.

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