Up
Ragweed pith
Primary pit fields
Primary pit fields
Wall, face view
Nucleate cells
Compact parenchyma
Sclerenchyma
Intercellular spaces
Leaf, xs
Chlorenchyma
Shoot tip, ls
Apical meristem
Vascular cambium
Secretory duct
Resin canal
Clusia duct
Root cortex
Leaf aerenchyma
Air chambers
Air chambers
Aerenchyma, Acorus
Stellate cells
Epidermis
Endodermis
Phloem, ls
Phloem, xs
Transfer cells
Bean cotyledon
Acorn, starch
Potato starch
Ice plant cell
Tannin cell
Small cells

Fig. 3.1-6. Transverse section of stem pith of sunflower (Helianthus). This parenchyma tissue is unusual in that all the component parenchyma cells (remember that parenchyma is both a type of cell and a type of tissue) abut each other with no visible intercellular spaces. Parenchyma tissue varies from having only tiny intercellular spaces as here, or much larger ones. Note how straight the cell walls are: all cells are equally turgid – they must all have the same vacuolar pressure pushing the walls against each other. If one cell was more pressurized than its neighbors, its walls would push theirs back – it would be more rounded and the neighbors’ walls would be concave.