(Ker Gawl.) Haworth Supplementum Plantarum Succulentarum. 79, 1819
Herbarium; Herbarium; Herbarium; Herbarium; Herbarium; Herbarium; Herbarium; Herbarium; Herbarium; Drawing (Britton and Rose, v1 1919, plate XXVIII, No. 2); Drawing (Botanical Register 1817, 3: plate 255)
What is Opuntia dillenii?
Opuntia dillenii is a coastal prickly pear cactus of the southern Atlantic states , the Caribbean Islands, the Gulf Coast of Mexico and Northern South America.
O. dillenii may reach 1 m tall but can reach 2 m in older groupings. Extensive stands sometimes make impenetrable thickets a meter tall. Pads are often 10 × 16 cm but may be smaller or larger. The areoles have 1 to 5(10) yellow or brownish-yellow spines. Spines may be 2-4 cm long. Areoles are raised above the cladode surface creating a dimpled look. Scalloped and dimpled cladodes with ample spines create a distinctive appearance in this Opuntia.
Yellow flowers produce reddish-purple fruits. They style is pale and the stigma is yellow. Filaments are yellow-green or green. Fruits are oval or spherical with pronounced, almost stipe-like necks. The umbilicus is moderately shallow. Areoles are clustered towards the top of the fruit.
This prickly pear has spread to other continents including South America, Africa, Australia, and Asia and is an invasive plant disrupting pastures, croplands, and natural habitats. The species is often confused with O. stricta, and this has obscured its actual current and former distribution. One reason for its weediness may be its ability to grow in various habitats such as woodlands, grasslands, creek banks, and disturbed areas such as roadsides even though it is considered a coastal species. It also tolerates a variety of soils and mild frosts.
Some botanists treat O. dillenii as a variety of O. stricta, and some treatments don’t even recognize it. Both plants may grow in similar habitats, but they are dissimilar. One important (but not universal) difference is that O. dillenii has pads with scalloped edges, whereas O. stricta does not. Additionally, O. dillenii it is a much spinier Opuntia than O. stricta. O. zebrina of southern FL may be a form of O. dillenii. Various ploidies have been reported for O. dillenii but it may be hexaploid. If different ploidies exist, the variants may represent two or more taxa. See the original description.