Opuntia pyrocarpa, large Texas prickly pear cactus

Griffiths, Bulletin of the Torrey Botanical Club 43(2): 90, 1916

Isotype; Herbarium; Herbarium; Herbarium; Herbarium (O. griffithsiana); Herbarium (O. griffithsiana); Herbarium (O. reflexa); Herbarium (O. convexa); Painting; Painting (O. convexa)

Original Description

**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.

Details

O. pyrocarpa is an ascending spreading plant to 1 m tall, but it may be lower. 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 curve in new cladodes outwards and down or they may be straight. Spines are present on the upper 50% to 60% of the areoles, 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 pale stigma. The petals are irregularly cleft or even nearly bifurcated. The fruit is pyriform or long-pyriform, and various shades of carmine, often with a purplish tinge outside and inside.

Ploidy is unknown.

Other Notes

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 may reach upwards to 80 cm. Several large plants growing together can create a formidable thicket. The species occurs along with other large prickly pears found in Texas, such as O. lindheimeri and O. orbiculata as well as multiple small species. Because it can form a large plant, O. pyrocarpa is confused with O. lindheimeri in parts of Texas, even though it is not upright. Also, O. pyrocarpa lacks the characteristic all-yellow spines of O. lindheimeri. The type location is Marble Falls, Texas.