For examining a cross-section of a plant stem under an optical microscope, several chemical dyes are recommended. Crystal violet is a common stain for basic microscopy, while phloroglucinol specifically highlights xylem cells, and toluidine blue differentiates xylem and phloem by staining xylem blue-green and phloem pink. Although food dyes could potentially work, their effectiveness is uncertain, and it's advised to test them first. For sourcing these dyes, local science education stores in the US may carry them, and online options like Carolina Biological Supply offer a variety of stains. Additionally, some tropical fish medications, available at pet stores, may serve as effective plant cell stains, particularly those that are blue or green. If local chemical dispensaries do not stock these items, online ordering is a viable alternative.
