Do monocot stems show secondary growth?

False (generally). The vast majority of monocot stems do not exhibit secondary growth because they lack vascular cambium, the lateral meristem responsible for producing secondary xylem and phloem. However, a few exceptional monocots do show secondary growth, making the statement "few monocot stems show secondary growth" true. Examples include certain palms (like Dracaena and Yucca), bamboos, and some members of the Agave family. These exceptional monocots have evolved alternative mechanisms for increasing stem diameter, sometimes through anomalous cambial activity or through a special type of meristem. The typical monocot stem relies on primary growth alone, with vascular bundles scattered throughout the ground tissue and a characteristic lack of a continuous cambial ring.