Griffiths, Annual report Missouri Botanical Garden 20: 90, 1909

Holotype; Topotype; Herbarium (as O. engelmannii); Painting

Original Description

What is Opuntia canada?

Opuntia cañada is a large, erect, ascending cactus that grows in far southern Arizona. It is a compact-appearing prickly pear.

Details

Opuntia cañada grows either singly or in dense thickets. Plants typically reach up to 1 m in height, though taller specimens are known. They are often slightly wider than tall. Cladodes are ovate to obovate, averaging approximately 16 × 22 cm, though size can be quite variable, especially in younger pads.

Areoles are initially brown but darken to black with age, often retaining a brown center due to continuous development of new wool. Spines may not appear until the cladodes are two years old but can become prominent thereafter. Spine color is variable, often yellow when young and fading to white with age. Each areole typically bears (1)2–3(5) spines, each about 12–15 mm long, with both spine length and number increasing on older growth. The species generally has fewer spines per areole than O. engelmannii.

The flowers are yellow, often with reddish or orange tinges at the bases of the inner tepals. The style is white or white with reddish tones, and the stigma is bright green. Fruits are variable in coloration, ranging from light red to mottled red and yellow. Seeds are thick, angular, and flat, measuring 3–3.5 mm in diameter, with a prominently notched hilum.

Ploidy is unknown.

Other Notes

O. cañada shares some similarities with spiny forms of O. laevis; however, the two species are consistently distinct. Opuntia laevis typically grows on canyon walls or among the rocky debris at their base, while O. canadensis occurs in deeper soils, often along canyon floors. The cladodes of O. laevis are longer and more narrowly shaped. In addition, O. laevis produces hairy seedlings and longer fruits, whereas O. canadensis seedlings are glabrous and its fruits are shorter.