Mammillaria muehlenpfordtii, commonly known as the Royal Cross Mammillaria, is a rapidly growing succulent cactus native to semi-desert habitats and rocky outcrops in the Mexican states of Guanajuato, Querétaro, and San Luis Potosí, typically found at elevations of 5,600 to 7,900 feet. It forms large clusters reaching up to 12 inches in height and width, with distinctive gray-green cone-shaped tubercles covered in drooping bristles. Each tubercle is adorned with 30-50 white to whitish-yellow radial spines, and the plant produces carmine red flowers in a wreath-like arrangement around the top of the stem, followed by bright red fruits containing brown seeds. The flowering season usually occurs in late spring to early summer, and the flowers are quite showy, adding to the plant’s ornamental value.

The Royal Cross Mammillaria is highly regarded for its ease of cultivation and striking appearance, making it a popular choice for rock gardens, container planting, and as a houseplant. It requires minimal maintenance, thriving in well-draining soil and with low water needs, typical of cacti. It prefers full sun to partial shade and can tolerate drought conditions. While generally pest-resistant, it can be susceptible to root rot if overwatered. This species is not known for being invasive but should be protected from frost to prevent damage.CC BY-SA 4.0