Q.47. In natural condition, which of the following plants DOES NOT exhibit anomalous secondary
growth?
(A) Rice
(B) Aloe
(C) Yucca
(D) Dracaena
The correct answer is (A) Rice. Most monocots lack secondary growth due to absent vascular cambium, but exceptions like Aloe, Yucca, and Dracaena show anomalous forms naturally. Rice follows typical monocot patterns without such growth.
What is Anomalous Secondary Growth?
Anomalous secondary growth refers to unusual stem thickening in plants, especially monocots, via modified cambium instead of standard vascular cambium. This produces secondary xylem and phloem atypically, often in patches or successive rings. It occurs naturally in certain woody monocots for structural support.
Option Analysis
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Rice (Oryza sativa): A grassy monocot with closed vascular bundles and no cambium, so no secondary growth occurs naturally. Stems remain herbaceous without thickening.
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Aloe: Exhibits anomalous growth through successive cambia forming outside primary phloem, producing secondary tissues for thicker stems and leaves. Common in Aloe vera.
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Yucca: Shows anomalous cambium from hypodermal meristems, generating vascular bundles and parenchyma for woody stems.
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Dracaena: Features secondary thickening meristem producing conjunctive tissue and vascular bundles, enabling tree-like growth.
Why Rice Stands Out
Rice, as a cereal grass, prioritizes rapid primary growth over girth increase, lacking the meristems seen in arborescent monocots like the others. This makes it the exception in natural conditions.
