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Why does cutting off the top of a branch make a plant grow bushier?
AIt removes the apical bud, freeing axillary buds
BIt removes the axillary buds, freeing the apex
CIt removes the lateral meristem, adding girth
DIt removes the cork cambium, adding new bark
Answer & Solution
Correct answer: A. It removes the apical bud, freeing axillary buds
1. The apical bud exerts apical dominance, which diminishes the growth of axillary buds along the sides of stems and branches.
2. Removing the apical bud lifts that suppression.
3. The axillary buds then start forming lateral branches.
4. More lateral branches is exactly the bushy shape gardeners want when they prune.
5. Removing axillary buds would do the opposite and leave a single leader, so the second option inverts the mechanism.
6. Lateral meristem and cork cambium govern thickening and bark rather than branching, so neither explains a bushy crown.
_Source: OpenStax Biology (1st ed., CC BY 4.0), Ch 30 "Plant Form and Physiology", section 30.2 Stems_
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