Benson 1982, FNA 2003

Common Name: greenflower nipple cactus Duration: Perennial Protected Status: Salvage restriced status in Arizona. General: Unbranched plant with flat topped stems that tend to be spheric to short cylindric with 6-15 tubercles and axils that appear naked, the cortex and pith are mucilaginous but with no latex. Spines: Spines 19-31 per areole and usually white or brownish off white and glabrous with 15-23 radial spines that are bristlelike and stiff, the 1-2 central spines extending forward and all hooked, these 10-20 mm long by less than 1 mm wide, the radial spines arranged in a circle and spreading parallel to the stem so that they appear to wrap around it. Flowers: Flower 2-3.5 cm long by 2-3 cm in diameter with the outermost tepal margins long fringed and reaching to 1 mm, with the inner tepals usually white, cream, tan, to even pale rose pink and sometimes pale orange, the anthers are yellow with sharply defined pink midstripes and suffused with other colors, these all 12-17 mm long. Fruits: Fleshy green or purple and ovoid or obovoid, 10-16 mm by 6-12 mm and juicy throughout. Ecology: Found on canyon slopes, grasslands, chaparral, and woodlands, often in gravelly substrates from 3,000-6,500 ft (914-1981 m); flowers in spring. Notes: Sometimes difficult to distinguish from M. wrightii, except with the petal color clearly separating them, and also the presence of green nipples and usually more than one hooked spine. Ethnobotany: Unknown, but other species in the genera had uses. Etymology: Mammillaria comes from the Latin mammilla, a nipple, while barbata means barbed. Synonyms: Mammillaria orestera, Mammillaria viridiflora Editor: SBuckley, 2010