Can a Mimosa ever be yellow?

[Finn N Rasmussen]

The genus Mimosa is said to contain about 400 spp. The most common sp. is 
probably the widespread weedy Mimosa pudica, which has pink flowers.  The cut 
off branches often sold as "Mimosa" are actually yellow flowered Acacia's, 
e.g. A. decurrens.  My question is:  Do all 400 true mimosa's have pink 
flowers? Can you be certain that a "yellow Mimosa" is never a true member of 
the genus Mimosa L.?

Finn N. Rasmussen, Botanical Laboratory,  Copenhagen. Univ.