(a) Why is sphagnum used as packing material for trans-shipment of living material ?
(b) Why are root-like structures of bryophytes called rhizoids ?

Explanation

(a) Sphagnum plant has capacity to retain ample amount of water for longer duration. That is why, they are used as packing materials so that the living materials continue to get water during the shipment.
(b) The rhizoids arise from gametophytic plant body whereas roots arise from sporophytic plant body.