The Collaborative International Dictionary of English v.0.48:

Acrogenous \Ac*rog"e*nous\, a. (Bot.)
   Increasing by growth from the extremity; as, an acrogenous
   plant.
   [1913 Webster]

WordNet (r) 3.0 (2006):

acrogenous
    adj 1: pertaining to flowerless plants (ferns or mosses) in
           which growth occurs only at the tip of the main stem
           [syn: acrogenic, acrogenous]