Melocactus ernesti is one of the Turk's cap cacti, and is native to Bahia and Minas Gerais States, Brazil.

There are 9 to 13 more or less rounded ribs or ridges with a slightly sharp edge, each with a row of spines usually about 1 to 2 inches (2.5 to 5 centimeters) long.

[2][3] The 7 to 13 straight or outwardly curved radial spines reach lengths of 4 to 15 centimeters.

The cephalium is the red, columnar, formed from more or less pink-red bristles, which is rarely covered with white wool at the top, is up to 18 centimeters high and reaches a diameter of up to 8 centimeters composed of hundreds of small, tightly packed flowers and grows a little longer each year.

The light to dark magenta pink flowers are 1.95 to 2.9 inches long and have a diameter of 9 to 18 millimeters.