MP Board · Class 9 · Science · TissuesCompare Xylem and Phloem tissues based on their constituent elements, cellular living condition, and direction of transport within the plant.
Xylem and Phloem are the two complex permanent tissues that constitute the vascular system of plants. They differ significantly in the following aspects:
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Constituent Elements: Xylem consists of four main elements: tracheids, vessels, xylem parenchyma, and xylem fibres. Phloem is composed of sieve tubes, companion cells, phloem parenchyma, and phloem fibres.
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Cellular Condition (Living vs Dead): In xylem, three out of four elements (tracheids, vessels, and fibres) are dead cells with thick lignified walls at maturity; only xylem parenchyma is living. Conversely, in phloem, three elements (sieve tubes, companion cells, and phloem parenchyma) are living cells, while only phloem fibres are dead.
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Direction of Transport: Xylem transports water and dissolved mineral nutrients unidirectionally from roots upward to the leaves and upper aerial parts of the plant. Phloem transports organic food (sucrose and photosynthates) bidirectionally from leaves to all other parts, including storage organs and growing tips.