Question

Plants having little or no secondary growth are

• A. Cycads
• B. Grasses
• C. Conifers
• D. Deciduous angiosperms

Answer 1

The Correct Option is B

The question asks to identify the type of plants that exhibit little or no secondary growth. Let's understand the concept of primary and secondary growth in plants to answer this question.

Primary growth in plants is associated with the extension of the plant body, resulting in lengthening of the roots and shoots. This occurs at the apical meristems located at the tips of roots and shoots.

Secondary growth, on the other hand, leads to an increase in the girth or thickness of the plant. This growth is due to the activity of the lateral meristems, namely the vascular cambium and cork cambium, predominantly found in dicotyledons and gymnosperms.

Now, let's evaluate each option:

1. Cycads: Cycads are gymnosperms and typically undergo secondary growth due to the presence of a vascular cambium. Thus, they show significant secondary growth.
2. Grasses: Grasses are monocotyledons. In monocots, secondary growth is rare or absent due to the lack of a vascular cambium. Therefore, monocots, including grasses, mostly show only primary growth and exhibit little to no secondary growth.
3. Conifers: Like cycads, conifers are also gymnosperms. They have a vascular cambium and consequently show marked secondary growth.
4. Deciduous angiosperms: These are typically dicotyledons, which possess a vascular cambium. They undergo secondary growth that contributes to the annual rings seen in tree trunks.

Upon analysis, Grasses are the plants with little or no secondary growth due to their monocot nature, which generally lacks secondary thickening. Hence the correct answer is:

Correct Answer: Grasses