News of the WeekPlant Biology

Xylem May Direct Water Where It's Needed

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Science  26 Jan 2001:
Vol. 291, Issue 5504, pp. 571-572
DOI: 10.1126/science.291.5504.571A

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For decades, researchers have seen the xylem as a column of dead tissue, like a worn pipe, that sits inside plant stems passively supplying water to thirsty leaves. But in a paper published online today by Science (, a team of plant biologists reports that gels in key xylem membranes constantly shrink and swell. With this motion, the xylem actually adjusts the flow of mineral-rich water coursing toward leaves.