What type of phyllotaxy is observed when a single leaf arises at each node in an alternating fashion, as seen in China rose, mustard, and sunflower?
Answer and explanation
Correct answer: A. Alternate phyllotaxy
- Step 1: Phyllotaxy is the pattern of arrangement of leaves on the stem or branch.
- Step 2: When a single leaf arises at each node on alternate sides of the stem axis, it is known as alternate (spiral) phyllotaxy.
- Step 3: Examples include Hibiscus rosa-sinensis (China rose), Brassica (mustard), and Helianthus (sunflower).
Answer
Alternate phyllotaxy
Why not the others: 'Opposite decussate phyllotaxy' features a pair of leaves at each node arranged at right angles to the pair above and below (e.g., Calotropis); 'Opposite superposed phyllotaxy' features leaf pairs at successive nodes lying in the same vertical plane (e.g., Psidium guajava); 'Whorled phyllotaxy' features more than two leaves arising at a single node forming a whorl (e.g., Alstonia, Nerium).
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