Bryophytes are non- vascular plants. They are called thus due to the absence of vascular tissue. They does not have either xylem or phloem. They don't have seeds . They does not contain lignin.They does not have any specialised tissues for water conduction.I have told earlier that xylem phloem calls are absent here, so water transport and food transport will not take place. So to avoid death due to the absence of this life saving process, they maintain osmosis to take this process on.