Botany - B.E. Yakubenko 2017

Part One. Plant Anatomy and Morphology
Chapter II. Histology
2.6. Fundamental Tissues (Parenchyma)

These Tissues are also referred to as filling tissues, as they occupy the spaces between the vascular and mechanical (structural) tissues. Intercellular spaces are well-developed within fundamental tissues. Depending on their specific function, origin, and Cell Structure, fundamental tissues are classified into several types: assimilatory, storage, Water-storage, and aerating (aerenchyma).

Parenchyma tissues originate from Primary and secondary Meristems. Assimilatory parenchyma contains METABOLISM/14.html">Chloroplasts and is involved in Photosynthesis. It is found in leaves, the stems of annual plants, and floral sepals. In leaves, a distinction is made between palisade and spongy parenchyma, whereas in the needle-like leaves (needles) of gymnosperms, folded parenchyma occurs.

Storage parenchyma serves as a site for nutrient reserves and is characteristic of roots, stems, seeds, and fruits. Its Cells are large, parenchymatous in shape, and possess thin walls. For instance, potato tubers accumulate starch, the parenchyma of beetroot roots and sugar cane stems stores sugars, and sunflower seeds accumulate oils, Proteins, and starch.

Aerating parenchyma, or aerenchyma, is located in the stems, rhizomes, and leaves of aquatic and marsh plants. It features large intercellular spaces filled with air.

Water-storage parenchyma Functions as a reservoir for water and is typical of so-called succulents—plants growing in arid environments that accumulate water in their stems or leaves. Examples include cacti, certain spurges (Euphorbiaceae), and aloe.

The absorptive or suction parenchyma includes the ROOT epiblem, which simultaneously performs a protective function.