Plant of the Week
Opuntia humifusa range map. USDA PLANTS Database.
Flower close up. Red center form. © 2011 David Taylor.
Looking down on green fruits. Note glochids and true leaves around top. © 2011 David Taylor.
View of a clump with flowers. Note spines. © 2011 David Taylor.
Eastern Prickly Pear (Opuntia humifusa (Raf.) Raf.)
By David Taylor
Eastern prickly pear is in the Cactaceae (Cactus) family. This family contains about 1,800 species all but possibly one or two native to the New World. The prickly pears are considered an old group within the cactus family with about 150 species in Opuntia. It has the largest range of any cactus in the United States and can be found from New Mexico and Montana east to Florida and Massachusetts. It is also found in Ontario. Eastern prickly pear can form large colonies or occur as a few individuals in an area. In older botanical manuals, it is often listed as Opuntia compressa.
This species is a typical cactus with a photosynthetic stem that acts as a leaf. This stem also stores water. Because of special antifreeze chemicals in its cells, it can survive the freezing temperatures of the northern and middle states. The stems or pads as they are often called can be 5 to 17 centimeters (2 to 7 inches) long and 4 to 12 centimeters (1.5 to 5 inches) wide. Pads are jointed in a linear or branched fashion.
Generally, the plants are no more than 0.5 meters (19 inches) high and tend to sprawl on the ground. Some Florida plants are shrub-like and can reach 2 meters (6.5 feet) high.
The pads are dotted with small dot-like structures called areoles. Each areole contains glochids (small barbed hairs-painful and irritating when in the skin) and may or may not have a spine in the center. Sometimes small green structures are found associated with each areole at the tip of new or actively growing pads. These are actual true leaves, but they soon fall off.
Flowers are produced at the ends of pads in early summer. They are usually yellow, but east of the Appalachian Mountains and on dunes, the center is often red to orange. The flesh of the reddish fruits is edible, but not usually very sweet unlike some other species such as the Indian Fig, Opuntia ficus-indica.
This cactus grows in open, dry areas, often on calcareous rock or thin soils. It can be found in or on fencerows, roadsides, rocky glades, rock outcrops, cliffs, old quarries, dunes, and prairie. The roots need to be dry during winter to prevent rot, so well drained sites are necessary.