Tripsacum, 7’. floridanum and especially 7°. zopilotense, 
have a delicate habit of growth approaching that of Mani- 
suris, while the other species of ‘T'ripsacum are more mai- 
zoid (maize-like), especially 7". australe and 7. maizar. 
Tripsacum, like maize, is confined to the New World. 
A preliminary survey of seven species of T'ripsacum was 
made by Cutler and Anderson (1941); and since then 
two additional species have been discovered (Hernandez 
X.and Randolph, 1950). Although taxonomically Mani- 
suris is often confused with Rottboellia and Hemarthria, 
it is clear that Manisuris has a world-wide distribution 
(Bor, 1960) and that at least five of its 12 or 18 species 
are native to the New World (Hitchcock, 1930, 1935). 
The differentiation of l'ripsacum into nine diverse spe- 
cies distributed throughout much of the New World 
suggests a considerable age for this genus, perhaps as 
much as 2,000,000 years. On the same basis, Manisuris 
would seem to be even older, an obvious requirement for 
a parent of ‘T'ripsacum, since Manisuris has differentiated 
into an even greater number of species (12 or 18) and has 
a world-wide distribution. 
The finding of nine chromosomes in Manisuris cylin- 
drica by Reeves and Mangelsdorf (1985) suggested to 
them that this grass was related to T'ripsacum. In further 
developing this idea, Anderson (1944) states: ‘‘ The cy- 
tological evidence would suggest that the 18-paired 'Trip- 
sacum might have acytological formula of X XY Y where 
X and Y stand for sets of 9 chromosomes, and that Mani- 
suris might be X X on the same notation.’’ On the basis 
of frequency of chiasma configurations per cell, Anderson 
postulated further ‘‘that the 86-paired varieties (of 'T'rip- 
sacum) arose as octoploids (XXYYXXZZ) between 
XXYY and XXZZ varieties.”” Anderson made no sug- 
gestion about the origin of the YY and ZZ genoms, and 
there is no reason to believe that the **Z’’ symbol in his 
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