Answer:
Because they require a WATER medium for reproduction
Step-by-step explanation:
Ferns are a group of living organisms under the division; Pteridophyta while mosses belong to the group Bryophyta. Mosses are considered primitive and non-vascular plants because they lack true stems, leaves and roots or vascular tissues. while ferns possess these organs, hence, are said to be vascular.
However, ferns and mosses are poorly adapted to a terrestrial life i.e. life on land because they both require a water medium for their motile male gametes to swim and fertilize their eggs (female gametes).