The label says this plant is a Mammillaria nejapensis but, according to Plants of the World Online by Kew, Mammillaria nejapensis is a synonym of Mammillaria karwinskiana.
Mammillaria karwinskiana Mart. is now the correct and accepted name for this species. It was named and described by Carl (Karl) Friedrich Philipp von Martius in Nova Acta Physico-Medica… in 1832.
The synonym, Mammillaria nejapensis R.T.Craig & E.Y.Dawson, was named and described by Robert T. Craig and Elmer Yale Dawson in Allan Hancock Foundation: Occasional Papers in 1848.
I bought this plant from Lowe’s on clearance on September 21, 2018. The label says:
“Native to Oaxaca, Mexico, forms globular stems with silvery white spines, dense wool at the areoles. Becomes slightly columnar, branching to form large clusters. Flowers are pale yellow with reddish midstripe. Water thoroughly when soil is dry.”
The plant is growing in a 4 oz. (2 1/2” diameter x 2 1/4” tall) pot. The plant measures approximately 1 7/8” tall x 2 3/16” wide without the spines.
Origin: Central and Southwest Mexico and Guatemala
Zones: USDA Zones 9b-11 (25-40° F)
Size: Hmmm… Maybe up to 8” or so tall.
Light: Sun to light shade. If grown inside over the winter, you should gradually increase the amount of light gradually when you put them outside.
Soil: Very well-draining soil. Potting soil amended with grit and price or perlite.
Water: Average during the summer and very seldom during the winter. Allow to dry out between watering
Mammillaria karwinskiana is one of only a few Mammillaria species commonly referred to as “Owl Eye Cactus” known for their dichotomous branching. I think this means the plant (stem) divides into two parts. Then the two become 4 and so on… I haven’t experienced this yet, be but could get interesting.
As with most Mammillaria species, maybe all of them, the entire plant is covered with spined tubercles. With this species, there are no central spines. The radial spines start out reddish brown then turn white as the plant grows. The areoles are covered with wool.
I will continue adding more photos and information as time goes by. This one will be interesting to watch and see how long it takes the stem to split. 🙂
I hope you enjoyed this page and maybe found it useful. If you have any comments, questions or suggestions, I would like to hear from you. Please click on “like” if you visited this page. It helps us bloggers stay motivated. 🙂 You can check out the links below for further reading. The links take you directly to the genus and species of this plant.