The genus Mammillaria is the largest in the cactus family (Cactaceae), with currently 171 known species and varieties recognized. Most of the Mammillaria are native to Mexico, but some come from the southwest USA, the Caribbean, Colombia, Venezuela, Guatemala and Hondura. This genus is the most popular one among cacti. There are societies throughout the world that strictly consist of Mammillaria aficionados, and there are collectors who specialize in this genus exclusively. New species are still being encountered in nature to this day; it is estimated that during the past 30 years some 50 new species have been discovered. The first was described by Carolus Linnaeus as Cactusmammillaris in 1753, deriving name from Latin mammilla, "nipple", referring to the tubercles that are one of the plant's specific features. The distinctive feature of the genus is the specific development of an areole that is split into two clearly separated parts, one occurring at the tubercle's apex, the other at its base. The apex part is spine bearing, and the base part is always spineless, but usually bearing some bristles or wool. The base part of the areole bears the flowers and fruits, and is a branching point. The apex part of the areole does not carry flowers, but in certain conditions can function as a branching point as we. The plants are usually small, globose to elongated, the stems from 1 - 20 cm in diameter and from 1 - 40 cm tall, clearly tuberculate, solitary to clumping forming mounds of up to 100 heads and possess radial symmetry. Tubercles can be conical, cylindrical, pyramidal or round. The roots are fibrous, fleshy or tuberous. The flowers are funnel-shaped and range from 7 - 40 mm and more in length and in diameter, from white and greenish to yellow, pink and red in color, often with a darker mid-stripe; the reddish hues are due to betalain pigments as usual for Caryophyllales. The fruit is berry-like, club-shaped or elongated, usually red but sometimes white, yellow or green. Some species have the fruit embedded into the plant body. The seeds are black or brown, from 1 - 3 mm in size.