Which one of the following tissues is known as basic packing tissue and found in xylem and phloem ?

Parenchyma is widely recognized as the basic packing tissue in plants [2]. It is a versatile ground tissue that fills the spaces between other specialized tissues, providing structural support when cells are turgid. Parenchyma cells are living, typically possess thin cell walls, and are involved in vital metabolic processes such as photosynthesis, food storage, and secretion. Crucially, parenchyma is a component of complex vascular tissues; it is found as xylem parenchyma in the xylem and phloem parenchyma in the phloem [2]. While collenchyma and sclerenchyma provide mechanical support and flexibility, they do not serve as the primary 'filler' or packing tissue. Vessels, on the other hand, are specialized conducting elements of the xylem rather than a packing tissue [2]. Therefore, parenchyma is the correct tissue type that fits both descriptions.

Sources

1. [2] https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/plant-tissue