Alamo Area Master Naturalist Jessica Leslie is the author of this piece.
The photo below on the left, Prickly Pear with tunas at PHP by Wendy Drezek and most of the Prickly Pear in PHP are Opuntia engelmannii var. lindheimeri*. However, on a recent walk along the trail Dr. Floyd Waller pointed out another Prickly Pear species: Opuntia macrorhiza, the Plains Prickly Pear. The Plains Prickly Pear can be distinguished from the more common Prickly Pear by its short stature (less than a foot), whitish (not yellowish) spines, somewhat folded (wrinkled, curved) obpyriform (not orbicular) pads, more elongated (less round) tunas, and a flower with a reddish center.
The photo below on the right by Wendy Drezek is a Plains Prickly Pear in PHP. For additional information to help distinguish these species and other Bexar County Opuntia species see this link page 1. There are over 200 species of prickly pear cactus in the genus Opuntia. They are native only to the western hemisphere, but they have been introduced to other parts of the world.
* Opuntia taxonomy is unsettled. See this link page 2: “ANOTHER TAKE ON OPUNTIA SPECIES IN BEXAR COUNTY”
Plains Prickly Pear photo by Wendy Drezek 
Plains Prickly Pear photo by Wendy Drezek
FLAT, ROUNDED PADS – SPINES, GLOCHIDS, and TUNAS, TOO
THE Opuntia genus conists of 150-180 species of flat-jointed cacti. They typically grow with flat, rounded pads or platycades with two types of spines — the harder, fixed spines and the smaller, hair-like spines, termed glochids, The glochids easily detach from the cactus pad when in contact with another surface, including a prying hand! The cactus produces a fruit or tuna that can be red, wine-red, green or yellow/orange depending upon the species. The tunas are used to make jellies, candies and beverages. For you San Antonians, the fuchsia-colored juice is often added to tequila to make a famous “fiesta margarita!”
NOPALITOS
Have you ever eaten a Prickly Pear cactus? If so, hopefully you removed the spines first! Both the pad and the fruit are used as a food source. The spines are removed from the pads by “sanding” them in a grit medium or by burning them. The young stems or pads are often used as a vegetable or in a salad. In Mexican cuisine, the sliced or chopped pads, called nopalitos, can be found in egg dishes, salads, and in tacos.
THE STORY OF COCHINEAL
Cochineal by Wendy Leonard 
Cochineal by Wendy Drezek taken a neighborhood near PHP
Another important use of the cactus is the production of cochineal dye. The dye is actually made from an insect that feeds upon the Prickly Pear cactus. Have you ever noticed small, white, cottony mounds on a cactus pad? They are Dactylopius coccus, a scale insect that feeds off the moisture and nutrients in the cactus sap. If you smash the insect between your fingers, it turns an intense maroon red. The insect produces carminic acid that helps to deter the bug’s predators. The acid is removed from the body and eggs of the insect to make a deep red dye.
Just how valuable was cochineal? Early Mixtec Indians used cochineal to dye their clothing to show social status. They actually farmed the cactus, working to develop different colors of red dyes. When the Spaniards arrived in Mexico, they became enamored of the deep red dye. Clothing was dyed with cochineal and shipped back to Europe. They could not ship enough of the textiles to keep up with the demand, so they began shipping the actual cochineal to Europe. Cochineal became second only to gold in value, and many a ship skirmish arose over the precious cargo. After 250 years of Spanish domination of the dye, other countries became involved, and soon cochineal could be found all over the world.
In fact, whenever a natural red dye is desired, cochineal is still the popular choice today. Although artificial colors have replaced the use of natural ones, you can still find cochineal in several products today. Have you ever spread “bug juice” on your lips? Chances are, if you have used red lipstick, you have put cochineal dye on your lips. The two main uses of the dye are for red food coloring and for cosmetics, such as rouges and lipsticks. Anytime you notice these ingredients—carmine, natural red 4, CI 75470 or E120 natural coloring—the source is cochineal dye. It is used to color many fruit juices, such as Ruby Red Grapefruit juice, some brands of strawberry yogurt, tropical punch drinks, and watercolor paints. Look for these ingredients next time you purchase some of these items.
STATE PLANT OF TEXAS
Phil Hardberger Park is fortunate to have many Prickly Pear along its trails. The Prickly Pear was selected by the Texas Legislature in 1995 to be the State Plant of Texas. All members of the subgenus Opuntia (with flat stems) are considered the state plant. The park’s most frequently observed Prickly Pear cactus is the Opuntia engelmannii var. lindheimeri known to most people as the Prickly Pear. However, if you look especially closely, you may the Opuntia species, Opuntia macrorhiza, the Plains Prickly Pear. As you enjoy the visual splendor of these cacti, realize you are seeing the State Plant of Texas.
For more information for children see, Pokies and Pricklies.