by Richard Pearman

Created on: March 11, 2009

You've probably seen cacti (and sometimes other succulents) with small dried flowers stuck to them in rings round the top. You may also have noticed small cacti with small real flowers (I mean the flowers of the cactus) in rings round the top. I think the dried flowers are meant to imitate the real flowers that belong to the most popular genus of cacti Mammillaria. There are probably several species in the cactus section of your local garden centre. Oddly, for such a popular and common genus, Mammillaria has no generally recognised common name and the Latin name hasn't made its way into common usage.

This article is about plants that don't have common names so it's going to contain a lot of Latin names. You can use a search engine to look these up.

Mammillarias are desert type cacti in the sub-family Cactoideae, which means that they have fleshy (almost always) spiny stems with no leaves (although some have very large tubercles). The stems are normally green but some species have a lot of red pigments making them look brown. They're fairly small, usually less than 30cm high although some can form clumps 1m or so across. The flowers are usually only about 1cm across and produced in rings around the growing tips. They all have spirally arranged tubercles (bumps) with no sign of ribs (ridges). Unlike most cacti, the areoles (hairy patches that produce the spins and flowers all cacti and only cacti have them) are divided into spine producing parts, which are at the tips of the tubercles and flower/branch producing parts that are in the tubercle axils. If you look carefully, you will often see a small hairy patch at the base and above each tubercle. If your plant has flowers or branches, you will see that these also come from the axils (some species branch dichotomously and one oddball has flowers from both the tubercle axils and tubercle tips). They DO NOT have nectar secreting glands or groves on the upper side of the tubercles (if your plant has one or both of these things, it's probably a Coryphantha or Escorbaria). Almost all Mammillarias are native to North America and most are Mexican.

Each areole will normally have one or several central spines that arise from near the middle and point out from the plant. There are normally a greater number of radial spines that arise from the edge and point sideways, around the plant. This is true both for cacti generally and Mammillaria generally. Some Mammillarias have only central spines. Many have only radial spines. There

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