References for Euphorbiaceae
Moore, R.J. 1958. Cytotaxonomy of Euphorbia esula in Canada and its hybrid with Euphorbia cyparissias. Can. J. Bot. 36:547-559.
Wheeler, L.C. 1941. Euphorbia subgenus Chamaesyce in Canada and the United States exclusive of southern Florida. Rhodora 43:97-154, 168-205, 223-86.

Source for the Reference Lists

George W. Douglas, Del Meidinger and Jim Pojar. 1998-2002. Illustrated Flora of British Columbia.