The correct option is (c) 2 and 3 only.
Explanation
Collenchyma is a simple permanent tissue composed of living cells. It provides mechanical support and flexibility to the growing parts of the plant, such as young stems and the petiole of a leaf.
- Statement 1 is Incorrect: Collenchyma is typically found in the hypodermis of dicot stems and in leaf stalks (petioles). It is generally absent in the roots of plants. It is also usually absent in monocots.
- Statement 2 is Correct: The cells of collenchyma are living at maturity and are usually elongated. A defining characteristic is that their cell walls are irregularly thickened at the corners due to the deposition of cellulose, hemicellulose, and pectin.
- Statement 3 is Correct: Due to the thickening at the corners, collenchyma cells are compactly arranged and typically have very little or no intercellular spaces.
Key Takeaway: Collenchyma is a mechanical tissue consisting of living, elongated cells with unevenly thickened walls (rich in pectin) at the corners, primarily found in the aerial parts of dicots.