Flowers?

[Ctr for Russian and East European Studies]

Perhaps the even-odd problem of flowers can be traced back to the
numerical symbolism of the neo-Platonic and Pythagorean philosophers.
In those systems, even numbers represent the negative and passive
principle, while odd numbers, the positive and active.  Even numbers
are feminine, odd numbers, masculine.  In the classical period,

Plutarch advises that sacrifices to celestial gods be odd in number,
while sacrifices to chthonic deities (gods of the underword and the
dead), be even in number.  That is exactly the sort of thing that
tends to remain in folk tradition.