Thelocactus tulensis

Thelocactus tulensis is a solitary, spherical cactus, sometimes slightly elongated, with a dark dull green body up to 25 centimeters high and 8 centimeters in diameter. It has 10 ribs that are bulbous to cone-shaped, up to 2 centimeters high and in diameter, with thick, fleshy warts that have many edges. The areoles are woolly when young, at a distance of 2.5 centimeters, and later become naked. It has 6 to 8 radial spines that are initially brownish and then turn white, measuring only 1 to 1.5 centimeters long. Additionally, it has 1 to 3 central spines that are up to 4 centimeters long, straight or curved, and whitish to horn-colored with a dark tip.

The flowers of Thelocactus tulensis are widespread, measuring 2.5 to 5 centimeters long and 3.5 to 8 centimeters in diameter. Their color varies from silvery white to delicate pink, with a carmine red central stripe. The scar of the flower is pale yellow. The fruits are green to greenish-magenta or whitish-brown, measuring 11 to 18 millimeters long and about 7 to 10 millimeters in diameter. The seeds are dark with a finely tuberous testa cell pattern.^[2]

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  Flower buds
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  Plant habit

Thelocactus tulensis is native to the limestone hills in the Chihuahuan Desert in Tamaulipas, Nuevo León, and San Luis Potosí, Mexico at elevations of 1200 to 1900 meters.^[3]

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  Plant growing near Rayones, Nuevo Leon
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  Plant growing in habitat near San Roberto