Griffiths, Annual report Missouri Botanical Garden 20: 90, 1909
Opuntia canada is a large, erect, ascending shrub that grows in far southern AZ. It is a compact-appearing plant to about 3- or even 4-ft tall with ovate (or obovate) cladodes. Spines are variable. However, they may light, or bleached white, or even yellow with dark bases. Spines may be twisted but are not annular. The flowers are yellow but may be tinged with reddish or orange on the bases of the inner tepals. The stigma is bright green. O. canada shares similarities with spiny forms of O. laevis; however, the two are consistently different. Also, in contrast to O. laevis, O. canada has hairless seedlings. At Florida Canyon in AZ (the type locality) the fruit of O. canada stays light in color, often orange or pale reddish and green or peachy inside. Other populations may have darker fruit. See the original description.