The soybean genus Glycine is currently divided into two subgenera, Gly-cine and Soja (Hymowitz and Newell, 1981). The subgenus Soja includes soybean (G. max) along with its annual wild progenitor (G. soja), with which soybean can be readily crossed. The other subgenus, Glycine, contains at least seven perennial wild species, all of which occur in Australia.
D. Brown, A. H.; Grant, J. E.; Burdon, J. J.; and Grace, J. P.
"Research Notes : Australia : Wild perennial Glycine species as genetic resources for soybean
Soybean Genetics Newsletter: Vol. 11
, Article 7.
Available at: http://lib.dr.iastate.edu/soybeangenetics/vol11/iss1/7