GERMINATION OF SEEDS 



629 



the lower end of the axis of the embryo, growing through the colcorhiza 

 (Fig. 103) and the wall of the grain (pericarp). As the primary root elon- 



FiG. 139. Stages in the germination of a red oak {Quercus horcalis) acorn. Redrawn 



from Korstian (1927). 



gates lateral roots soon appear and root hairs begin to develop just back of 

 the elongating regions on all of the roots. The single cotyledon (scutellum) 



