318 . WEATHERWAX: THE EVOLUTION OF MAIZE 
placed by staminate spikes (Fic. 10). Emerson (13, p. 83) 
has isolated a dwarf variety which 
has perfect flowers in the ear. 
Gernert (15) has;isolated from a yel- 
low dent variety. a strain in which 
the ear is a loose panicle like that of 
one of the sorghums. The tassel is 
also branched more than in the typi- 
cal variety (Fic. 14), and many 
groups of spikelets are borne on pe- 
duncles instead of being in sessile 
groups (Fics. 15-19). A common 
type of variation consists of a nor- 
: mal ear bearing a whorl of small, 
Fics. 15-19. Peduncled groups 
of spikelets from Branch Corn, four-rowed branches around the base 
showing the probable steps inthe (FIG. 9). Ears variously divided or 
evolution of the pair of spikelets. — branched at the tip are also of com- 
mon occurrence. 
MorpHoLocy oF EuCHLAENA 
Without discussing the systematic treatment of Euchlaena, 
we may take Euchlaena mexicana Schrad. (synonymous with 
Euchlaena luxurians Dur. and Reana luxurians Dur.) as the type 
of the genus. It is the well-known teosinte, an annual forage plant 
of the warmer parts of America. The species is much less variable 
than maize. 
Teosinte has much the same general appearance as maize, 
especially since the casual observer’s mental picture of the latter 
is obtained from seeing two or three plants growing inaclump. It 
has the same sort of leafy stem, and the same potential branches 
in the axils of its leaves; but the branches arising from the base 
of the plant—ten to sixty or more in number—grow as tall as 
the main stem and resemble it in every way. These continue to 
branch indefinitely, a branch being possible at practically every 
node; generally speaking, a branch has about as many nodes 
as the main stalk above the point of branching. The main stalks 
and some of the higher branches are terminated by male panicles. 
At the top of any stem, the branches tend to be male, while the 
lower ones of the same order tend to be female. 
