352 LINDSTROM, GENETICAL RESEARCH WITH MAIZE 
mr — midrib. Leaf consists of but little more than midrib. 
ms — male sterile. Anthers produce no pollen. 
na — nana. Dwarf plant. 
nk — naked. Cob and tassel almost free from spikelets. 
P — pericarp and cob color. An allelomorphic series P’’, Pwr, etc. 
PI — purple plant color. Develops in local darkness. 
Pr — purple aleurone. Red aleurone-pr. 
R — , red’ aleurone. One of the complementary factors (ACR) for 
aleurone color, and also in an allelomorphic series affecting 
plant colors and pericarp: Ar RP, 77, 79, r°, etc. 
ra — vamosa ear. 
rs — spotted aleurone. 
sc — scarred endosperm. 
sh — shrunken endosperm. 
sl — slashed. Slashed or shredded seedling. 
sm — salmon silks. 4 
sp — spear. Spear-like seedling. Usually lethal. 
su — sugary endosperm. 
te — tasselear e | Two types producing only pistillate flowers 
ts — tassel seed e \ in the tassel. 
Tu — tunicate ear (pod corn). 
v — virescent seedling. (Complementary factors v, and vs). 
‘w — white seedling. ( 
ws — white sheath. 
wx — waxy endosperm. 
Y — yellow endosperm. Duplicate factors known. 
ys — yellow-striped leaf. 
zb — zebra-transversely striped leaves. 
zg — zigzag stalk; duplicate factor with z. 
De ” Wy ” Wa). 
Many of the above factors have been named and used by Dr. R. A. 
EMERSON of Cornell University and by his coworkers. Changes in the 
nomenclature are sometimes necessary in order to indicate new inter- 
relations, but usage has established most of the factors in this list more 
or less definitely. In the case of the biliteral symbols, the second letter 
may be placed as a subscript (4,4,s,s,) or the same relation may be in- 
dicated by proper spacing between the different allelomorphs (ab ab 
SU SU). | 

