Why are mechanical tissues lacking in bryophytes?

Bryophytes, which include mosses, liverworts, and hornworts, lack mechanical tissues because they are small, non-vascular plants that thrive in moist environments. They do not require the structural support provided by mechanical tissues like xylem and phloem, as they are able to maintain their shape and structure through turgor pressure. Additionally, their simple body plan and the absence of true stems and leaves reduce the need for such specialized support. Instead, bryophytes rely on diffusion for nutrient and water transport, which is sufficient for their size and habitat.