Mammillaria (2006)

By Pam Schnebelen (March 2006)

Dorothy Weitz has had a huge influence on my interest in plants. Dorothy was an excellent propagator who inspired my passion for this part of our hobby. Dorothy’s seed-grown cacti were famous for their blue ribbons in the HSCSS show, and Dorothy was generous in sharing her propagating experiences with others.

So as many people as possible can inherit Dorothy’s seed work, Janet Kister and I have been separating Dorothy’s seedling pans prior to this month’s sale. When I encountered her two blooming specimens of Mammillaria crucigera, I was inspired for this article.

While M. crucigera was described over 165 years ago, it is fairly new in cultivation. In the 1970s, the plant was rediscovered in Oaxaca, Mexico, growing on gypsum cliff faces. Most collectors find it a difficult species, but the strict symmetry and beautiful geometry of the tubercles and spines make it worth an effort.

This mamm sometimes offsets – as Dorothy’s seedlings have – and its stem will also divide dichotomously. The bright fuchsia flowers are small and, as in all mammillarias, occur in a ring around the apex of the plant.

Along with several other mamms, M. crucigera has better wool and spines if you add limestone to the potting mix. Other mamms that appreciate limestone amendments: M. carmenae, M. humboldtii, M. lasiacantha, M. leuthyi, M. nivosa, M. parkinsonii, M. pectinifera and M. schiedeana.

Mamms put on an exuberant flower show! Various shades of pink are the most frequent color, but whites and yellows are common. With our unusually warm January and February weather this year, my plants that bloom in early spring are beginning their display now. Revisiting my photographs as I prepped this article, I was surprised to see how diverse the blooming times are in this genus. Some examples:

Mammillaria lasiacantha ssp. denudata – January
Mammillaria scrippsiana – January/February
Mammillaria ritteriana – February
Mammillaria karwinskiana – February
Mammillaria parkinsonii – March
Mammillaria leptacantha – March
Mammillaria candida – April
Mammillaria theresae – April
Mammillaria herrerae – April/May
Mammillaria hernandezii – November
Mammillaria plumosa – October/November.

We think of mammillarias as Mexican cacti, but their range extends beyond the Mexican boundaries. The cold-tolerant M. tetrancistra is native to the southern parts of Utah and Colorado, and M. grahamii is a native plant in New Mexico and Arizona. Both of these plants are hardy to 10 degrees F – well below freezing!

On the other extreme of the temperature scale are mamms from Caribbean and South America. M. columbiana is from Columbia, Guatemala, Honduras, Curacao and the West Indies. M. nivosa is another of the few species found south of Mexico. Hailing from areas in and around Puerto Rico, this yellow-spined, white-wooled plant suffers horribly in the greenhouse during the winter. Instead, Mammillaria nivosa spends its winters in the house. Native to Guatemala and Honduras, M. voburnensis is another of the warm-winter plants.

Given their wide range of geographies, mammillarias have widely differing culture requirements. Most species are fairly easy to grow and some are – at least for me – impossible. When adding a plant to your collection, be sure to do some research into its origins and lifestyle. Not all mamms can be treated equally.

Google the species name. Look into the HSCSS library. My favorite mamm book is John Pilbeam’s Mammillaria. Produced as a volume of The Cactus File Handbook in 1999, it is stuffed with maps, photographs, habitat information and culture information. Our library has a copy.

On March 12, bring your mamms to the monthly meeting – both the prize winners and the plants that give you trouble. And bring those unnamed plants! Someone in the group might be able to label a tag for you.

Also … come prepared to adopt a mammillaria from Dorothy Weitz’s collection. Is there an M. crucigera on your wish list? How about a Mammillaria lenta sown in 1987? M. huitzilopochtli from 1974? M. angelensis from 1971? Come see what’s available!