The genus Glycine as currently delimited is divided into two subgenera Glycine and Soja. The subgenus Soja includes the soybean, G. max, and its annual wild counterpart, G. soja. The subgenus Glycine comprises seven wild perennial species.
"Research Notes : United States : The genus Glycine subgenus Glycine germplasm collection,"
Soybean Genetics Newsletter: Vol. 11
, Article 31.
Available at: http://lib.dr.iastate.edu/soybeangenetics/vol11/iss1/31