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From evolutionary point of view, tracheids and sieve cells are more primitive than tracheae and sieve tubes respectively. The angiosperms have |
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a) |
Tracheae and sieve tubes |
b) |
Tracheids, tracheae and sieve tubes |
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c) |
Tracheae, sieve cells and sieve tubes |
d) |
Tracheids, tracheae and sieve cells |
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From evolutionary point of view, tracheids and sieve cells are more primitive than tracheae and sieve tubes respectively. The angiosperms have |
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a) |
Tracheae and sieve tubes |
b) |
Tracheids, tracheae and sieve tubes |
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c) |
Tracheae, sieve cells and sieve tubes |
d) |
Tracheids, tracheae and sieve cells |
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(b) In angiosperms, xylem consists of tracheids, vessels or tracheae, xylem fibres and xylem parenchyma. Tracheae are absent in pteridophytes and gymnosperms. In angiospermic phloem, sieve elements are sieve tubes, while in gymnosperms and pteridophytes sieves cells are found. |