Source : Webster's Revised Unabridged Dictionary (1913)

Acrogenous \Ac*rog"e*nous\, a. (Bot.)
   Increasing by growth from the extremity; as, an acrogenous
   plant.

Source : WordNet®

acrogenous
     adj : pertaining to flowerless plants (ferns or mosses) in which
           growth occurs only at the tip of the main stem [syn: {acrogenic}]