These images are superb examples of the eustele arrangement of primary vascular bundles. The above image is a t-blue stained cross-section which clearly shows the pith, cortex, and interfascicular parenchyma surrounding the vascular bundles. The phloem is closer to the surface of the stem than the xylem (the vessel members are clearly evident in the xylem).

The phloroglucinol stained cross-section below shows the heavily lignified xylem with the clearly evident vessel members and the phloem is not stained. The phloic fibers which are outside of the unstained phloem are stained red showing the thickened (lignified) walls and very small lumen.

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Below is an excellent view of the protoxlem stained with phloroglucinol. In this longitudinal section, the annular and helical thickenings are stained red reflecting the lignin content. Note the thin-walled, rather blocky pith parenchyma cells which lie centripetal to the xylem.

Overall primary growth can be nicely summarized in the following image which shows the elements discussed above in a phloroglucinol stained cross-section.