Question

Most aquatic plants do not have roots while most desert plants have very deep roots.why

Answer 1

The function of roots is absorb water and to anchor the plant to the ground. But most of the aquatic plants are floating and they have rhizoids to absorb water. In some plants the leaves absorb water. So, aquatic plants do not have roots. In desert there is scarcity of water. The soil is loose and dry. The roots go deep to hold the plant firmly to the ground and in search for water in the deeper layers of the soil.

Answer 2

because of presence of water.
aquatic plant lives in water therefore they get water from their root in upper side of the soil.
whereas desrt plant can't get water from upper part of soil they get water from lower side of soil.
for this reason desrt plant have long root than aquatic plant