Question

How many plants among China Rose, Ocimum, Sunflower, Mustard, Alstonia, Guava, Calotropis and Nerium (Oleander) have opposite phyllotaxy?
A. Four
B. Five
C. Two
D. Three

Answer 1

Phyllotaxy refers to the arrangement of leaves on the stem of a plant. When the leaves are present on nodes that are directly opposite to each other, it is referred to as the opposite phyllotaxy. The plants that show opposite phyllotaxy may be weeds, aromatic herbs, or even common fruit-bearing trees.

Complete answer:
Out of China Rose, Ocimum, Sunflower, Mustard, Alstonia, Guava, Calotropis, and Nerium, only three plants show opposite phyllotaxy.

The plants that show opposite phyllotaxy are:
- Ocimum
- Guava
- Calotropis

OCIMUM: Ocimum is an aromatic herb that is used in certain food items as a condiment. For example- Basil and Tulsi
GUAVA: The guava fruit grows on small trees in many tropical and subtropical regions.
CALOTROPIS: Calotropis is a flowering plant, however, it is considered to be a weed in certain regions. They produce latex.

Hence, the correct answer is option (D).

Additional information:
Other than opposite phyllotaxy, there are two other types of phyllotaxy.

Alternate phyllotaxy: When only a single leaf is present at a node in an alternate pattern, it is referred to as alternate phyllotaxy. Such an arrangement of leaves can be observed in China Rose, Sunflower, and Mustard.

Whorled phyllotaxy: When more than two leaves are present at a node, thereby forming a whorl, the arrangement is referred to as whorled phyllotaxy. Such an arrangement can be observed in Alstonia and Nerium.

Note: Phyllotaxy in plants is indicative of a well-structured arrangement. If there was no phyllotaxy, the leaves would have been arranged in a haphazard manner. This arrangement of leaves is influenced by the hormone auxin, that is present in the meristem. Leaves start developing in those areas of the stem which have low levels or absence of auxin.