Presented below is a photomicrograph showing a cross section of an herbaceous stem. This digital image was captured with the DXM 1200 ACT-1 control software in single-image acquisition mode utilizing apodized phase contrast illumination.

The stems of herbaceous plants are soft and flexible and are found typically on annuals, such as most vegetables, plants that grow for only one season. The herbaceous stem is composed of vascular bundles (xylem and phloem) arranged in a circle around a central core of spongy tissue made up of parenchyma cells, called the pith. Surrounding the vascular bundles is a layer known as the cortex, which varies in thickness from species to species. Surrounding this is a layer of cells called the epidermis.

The stem functions primary to support the leaves, to conduct water and minerals to the leaves where they can be converted into usable products by photosynthesis, and to transport the products of photosynthesis from the leaves to other parts of the plant, including the roots.