Tissues — Science STD 9 — Question

The different types of elements present in the phloem are:

1. Sieve tubes: Sieve tubes are slender, tube-like structures composed of elongated thin-walled cells, placed end to end. Their end walls are perforated by numerous pores and are called sieve plates.

2. Companion cells: It is a small thin-walled cell containing dense and very active cytoplasm and large elongated nucleus.

3. Phloem parenchyma: These are thin-walled, living cells of parenchyma of phloem. They have two functions, storage and slow lateral conduction of food.

4. Phloem Fibre: These are thick-walled, elongated spindled shaped dead cells which posses narrow lumen. They provide mechanical strength to the tissue.