Mineral nutrition and movement of substances

Water with dissolved mineral salts rises from the roots toward the leaves through dead vessels of the wood. This can be shown: put a leafy shoot in coloured water, and after 2–3 hours cut it — only the wood is stained. Organic substances made in the leaves (mainly sugar) are carried to other organs through the sieve tubes of the bast: sugar accumulates in the storage roots of carrot and beet and in the fruit and seeds of other plants, and turns into starch in a potato tuber. Second experiment: from two identical twigs of willow or poplar, a ring of bark is removed from one, and both are put in water; after two weeks roots appear at the lower end of the control twig, while on the ring-barked twig roots grow above the cut ring — organic matter cannot pass down and collects above the cut. So water and minerals move through the wood, organic substances through the bast. All organs depend on each other: if the root does not supply water, leaves make little organic matter. Pinching cotton directs organic matter to flowers and bolls.