Question

In hydrophytes xylem is less developed why

Answer 1

Water loss is not an issue for hydrophyte plants as water can be absorbed into the plant anywhere at any time. The plant does not need well developed xylem tissues in order to keep water balance as water can enter directly into the leaves and stem via osmosis.  

Answer 2

Xylem is less develop in hydrophytes because hydrophytes has access to abundant water. It mean water can easily diffuse in every part of plant and do not need to be transported through xylem.