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 41 fire hose DHJanzen100352.jpg high resolution
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| A vine crown may have as large a solar panel as does a small tree, layered out over the crown of a tree for support. This means that the vine must carry as much water up to those leaves as a tree trunk does. This cross section through a Costa Rican rain forest woody long-life vine (it could be 100 or more years old) is about 10 cm in diameter. It has enough cambium/meristem ability to repair wounds in its surface, but does not grow in diameter (i.e., it does not add wood to the stem annually as does a tree). It is in effect a fire hose. Look at this cross section in high resolution and note the enormous vessels for water transport. It may be moving as fast as several meters per second up the vine on a dry day. Note also that there is almost no space for storing reserves, at least nothing in comparison with the sapwood of a tree trunk. This is why all species of vines have a large underground tuber as their storage organ - a tuber that you know quite well, for example, as a sweet potato (which is a vine - Ipomoea - in the Convolvulaceae, as in image DHJanzen100348.jpg above). | ||
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