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BOTANICAL MUSEUM LEAFLETS 
HARVARD UNIVERSITY 
BRIDGE, MAssaAcHUsETTS, JUNE 26, 1957 
THE EFFECTS OF CERTAIN GENES 
ON THE OUTER PISTILLATE GLUME 
OF MAIZE 
BY 
Watton C. GALINAT 
A comparison of the effects which various genes have on 
the structure of a given plant-organ should sometimes 
reveal which of the loci concerned were involved in the 
previous evolution of that organ and which of them 
might, during domestication of the species, contribute to 
its further evolution. he extreme susceptibility of the 
outer pistillate glume’ in the maize tribe (Maydeae) and 
the related tribe 4 ndropogoncae to evolutionary modifi- 
cations suggests that the genetic variation affecting de- 
velopment of this organ in maize (Zea Mays 1) may 
reflect some of its evolutionary changes. The changes in 
glume structure were drastic during evolution leading to 
the formation of the cupulate fruit case (Galinat, 1956). 
This organ evolved from a long foliaceous bract (d’rian- 
thus spp.) to a shorter, coriaceous structure marked by 
various types of sculpturing (Manisuris spp. ; Hackeloch- 
loa spp.) and, finally, to a highly lignified glume which 
is specialized in shape, texture and plane of divergence so 
as to bring about a closure of the narrow opening of a 
cupulate rachis-segment (Muchlaena and Tripsacum). 
‘Further mention of the glumes of maize will refer only to the 
outer pistillate ones. 
