This phenomenon can result from mutations in the Abphyl1 gene of maize. A
search of Abphyl1 at pubmed (http://www.ncbi.nlm.nih.gov/) will pull up the
relevant literature, which suggests the root cause is a defect in cytokinin
response which leads to an expanded meristem.
--
Mark P. Running, Ph.D.
Assistant Member, Principal Investigator
Donald Danforth Plant Science Center
975 N Warson Rd
Saint Louis MO 63132
Phone(314) 587-1641
Cell(314)359-9344
Fax(314) 587-1741