Water is transported upward in a plant through xylem tissue, which consists of c
ID: 1794238 • Letter: W
Question
Water is transported upward in a plant through xylem tissue, which consists of cells of 1 mm length and a diameter of 335 µm. The xylem cells are attached to each other to form a channel. To what maximum height can water rise in these xylem channels due to capillarity? For those interested: Confirm this result with a simple experiment: Cut and split the stem of a flower with white petals (e.g., a dahlia or a carnation) and place one half the stem in a glass with dilute red ink and the other half in a glass with dilute blue ink. After several hours the flower will be half red and half blue.
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Explanation / Answer
Height h of liquid due to capillarity, is given by,
h = 2 T cos theta / r rho g
T is surface tension of liquid
theta, is angle of contact between liquid and material of capillary
r is radius of capillary
rho is density of liquid
Surface tension of water = 0.073 N/m
Considering completing wetting of plant by water, theta = 0
h = 2 * 0.073 *2 / 3.35x10-4 * 1000*9.8
= 0.089 m = 8.9 cm
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