Question

Which among the following plants is having both interxylary and intraxylary phloem in its stem?

• A. Cycas
• B. Leptadenia
• C. Calotropis
• D. Mirabilis

Answer 1

The correct option is B Leptadenia

Interxylary phloem is the secondary phloem on the inner side which is embedded within mass of secondary xylem. Intraxylary phloem is the secondary phloem present in the innermost region of primary xylem. Intraxylary phloem is present in pith region. Leptadenia stem shows conjoint bicollateral vascular bundles. Initially these vascular bundles behave normally of forming secondary xylem towards inner side and secondary phloem towards outer side. But later it produces small patches of secondary phloem towards inner side which are embedded in secondary xylem. These patches are termed as interxylary phloem. Intraxylary phloem is said to be formed by transformation the parenchymatous cells of the pith or from xylem parenchyma.
Thus, the correct answer is option B.