Griffiths, Bulletin of the Torrey Botanical Club 43(2): 90, 1916
What is Opuntia pyrocarpa?
Opuntia pyrocarpa is a commonly encountered prickly pear cactus in south-central to north-central Texas where it often grows in deep, limestone-derived soils. It is found in Mexico and perhaps Oklahoma, and it may be in other parts of Texas.
O. pyrocarpa is an ascending spreading plant to 1 m tall. Often the main branches of this prickly pear cactus are prostrate but ascend at the ends. The cladodes are large, approximately 25(30) × 15(20) cm, or they may be smaller in some plants. The cladodes may be constricted at the base to form a short neck, or this feature may be lacking. The spines are porrect in new cladodes, but often slope down with age. Spines are present on the upper 50% to 60% of the areoles and are yellow darkening to a brown base. Spines are 2 to 3 cm long.
The flowers are yellow with light-red centers or pure yellow. This Opuntia has a white style tipped with a light-green stigma. The petals are irregularly cleft or even nearly bifurcated. The fruit is long, pyriform, and various shades of carmine, often with a purplish tinge outside and inside.
Ploidy is unknown.
O. pyrocarpa may form large plants that create piles of cladodes spread over 6-8 feet, making up for lack of height by achieving breadth. Or prostrate ascending branches by reach upwards to 100 cm. Several large plants growing together can create a formidable thicket. The species occurs with others found in Texas such as O. lindheimeri, O. macrorhiza, and O. orbiculata, etc. The type location is Marble Falls, Texas.