Old Lady Cactus or Old Lady Pincushion

Mammillaria hahniana

mam-mil-AR-ee-uh  hahn-ee-AY-na

ROYAL HORTICULTURAL SOCIETY AWARD OF GARDEN MERIT

Synonyms for Mammillaria hahniana (15) (Updated on 12-8-23 from Plants ofthe World Online): Mammillaria bravoae R.T.Craig, Mammillaria hahniana subsp. bravoae (R.T.Craig) D.R.Hunt, Mammillaria hahniana subsp. mendeliana (Bravo) D.R.Hunt, Mammillaria hahniana var. werdermanniana F.Schmoll ex R.T.Craig, Mammillaria hahniana subsp. woodsii (R.T.Craig) D.R.Hunt, Mammillaria mendeliana (Bravo) Werderm., Mammillaria saetigera Boed. & Tiegel, Mammillaria saetigera var. quadricentralis R.T.Craig, Mammillaria saetigera subsp. woodsii (R.T.Craig) Rogoz. & Plein, Mammillaria woodsii R.T.Craig, Neomammillaria hahniana (Werderm.) Y.Itô, Neomammillaria hahniana var. werdermanniana(F.Schmoll ex R.T.Craig) Y.Itô, Neomammillaria mendeliana Bravo, Neomammillaria saetigera (Boed. & Tiegel) Y.Itô, Neomammillaria woodsii (R.T.Craig) Y.Itô

Mammillaria hahniana Werderm. is the accepted scientific name for this species of Mammillaria. It was named and described by Erich Werdermann in Monatsschrift der Deutschen Kakteen-Gesellschaft (Berlin) in 1929.

The genus, Mammillaria Haw., was named and described by Adrian Hardy Haworth in Synopsis Plantarum Succulentarum in 1812.

As of 12-8-23 when this page was last updated, Plants of the World Online by Kew, there are 138 accepted species in the Mammillaria genus. It is a member of the plant family Cactaceae with 150 genera. Those numbers could change as updates are made on POWO.

THERE ARE SEVERAL LINKS AT THE BOTTOM OF THE PAGE FOR FURTHER READING.

I brought my Mammillaria hahniana home from Walmart on 2-1-16. It was in a 2 1/2” diameter (4 oz.) pot. The plant measured approximately 1 7/8” tall x 2 3/8” wide. The label states:

“Native to Mexico, forms globular stems to 6” or more in diameter. Stems are densely covered with white hair and short white spines. Concentric rings of pink flowers. Protect from frost. Provide bright light/sun. Hardy to 20 degrees F. To 6” tall. Water thoroughly when the soil is dry.”

Mammillaria hahniana is one of the more popular Mammillaria species. It can be identified by its long, thin, white hair, and wool that can become more dense with age. The species is somewhat variable, of course, and some plants may have more wool and others more hair, which has led to numerous variations and subspecies which are all considered synonyms of the species.

Plants can have different shapes when young but become more cylindrical as they grow. As with all Mammillaria species, they have small nipple-like tubercles. Being a variable species, the hair-like bristles and wool growing from their axils can be long or short, straight or curly. 

The axil, which may be hard to understand from some definitions, is basically the area between the tubercles on cactus. You have to get a magnifying glass to tell, but there can be 20 or more of these “hairs” growing from the axils. On some plants, it is very hard to tell if the hair is coming from the axil or areole… Some specimens will be densely covered with wool coming from the axils others not so much. This can make it sort of difficult to tell if you have a Mammillaria hahniana or not… 

Ahhh, the areola… Areoles are at the tip of the tubercles and is where the spines emerge. Mammillaria hahniana can have 1-4 very short central spines. In addition, there are “can be” 20-30 radial spines that are also fairly hair-like. They can be from 5-15 mm long or they may even be absent… That is just over 1/4” to a little over 1/2” in mature plants but will be even smaller when young.

Small specimens of this species may have very little wool and be very hairy so if you purchase an unlabeled cactus at a store, trying to figure out what it is can be a time-consuming project. You look at hundreds of images and you can’t just quite figure it out… 

Mammillaria hahniana is native to Guanajuato, San Luis Potosí, and Queretaro, Mexico. The species grows along relatively steep slopes in submontane matorral and deciduous forests. This cactus is locally common where it occurs and grows in groups or clusters which are rare. Mammillaria hahniana is listed as near threatened in its native habitat because of its limited range and illegal collection. Some subpopulations are impacted by deforestation.

Many cacti are very slow growing so I take measurements from time to time. When I moved the plants inside for the winter on October 17, 2017, the Mammillaria hahniana measured 2 1/2″ tall x 2 3/4″ wide.

Remember to clean off your pots when you bring them inside for the winter. Remove dead leaves or other debris that might have been collected in your pots and on your plants. Check for unwanted guests that may be trying to hibernate around the base of your plants because you never know…

I like taking photos from the top of the cactus. Many of them grow in this neat spiral-looking pattern.

Information online says that Mammillaria hahniana is one of the fastest-growing of the Mammillaria genera and will form large groups. The wool is supposed to increase in thickness and length.

Mammillaria, like most cacti, are easy to grow if you follow a few basic rules. Check out my Cactus & Succulent Tips for my advice…

The Mammillaria hahniana is continuing to do well and is now happy on the back porch.

I had to move the potted plants inside for the winter on November 10. I always measure the cactus and succulents when I move them inside and the Mammillaria hahniana measured 2 5/8″ tall x 2 7/8″ wide. It was 1 7/8” tall x 2 3/8” wide when I brought it home on February 1, 2016.

November 29 was a nice spring-like day, so I took the cactus to the back porch for a photoshoot. I was working on a post to show the difference between the cactus in my collection.

The apex is in the center of the top of the plant. Many Mammillaria species apex is kind of concave. The axil, I think, is either the lowest part or where it starts to angle up. There are 20-30 spines in this area that appear to “unfold” as the plant grows. Be it ever so sssssllllloooowwwwllllyyyy…

Its white hair can cover the entire plant and increases in thickness and length as the plant ages. Each tubercle has 1-4 small central spines and 20-30 hair-like radial spines. Some specimens may not even have radial spines. Some Mammillaria species have latex in their tubercles and this one supposedly does…

<<<<2019>>>>

The Mammillaria hahniana is looking its AWESOME self on July 22.

I noticed the Mammillaria hahniana had a few buds on July 4. Its wool is wet in the above photo because we had rain.

I had to move the potted plants inside for the winter on October 11 because an “F” was in the forecast. As always, I took photos of all the plants and measured the cactus and part of the succulents. The Mammillaria hahniana measured 3 1/4″ tall x 3 3/8″ wide.

I really like this plant with all this wool! I wrote a Mammillaria update on November 16 which you can view by clicking HERE.

After the “F”, temperatures warmed up for a few days again. This always happens. The cactus were giving me dirty looks so I put them outside for a few days. I noticed the Mammillaria hahniana had a few buds.

As long as the cactus know it is cold outside they don’t mind being inside. Most of them are on a table in front of the sliding door, so they can tell when I go in and out.

<<<<2020>>>>

I had to move the potted plants inside for the winter on October 15 because an “F” was in the forecast. As always, I take photos and measurements. The Mammillaria hahniana did very well over the summer and measured 3 5/8″ tall x 3 5/8″ wide.

I had to take another photo of its flowers on 11-6-20…

THEN IT HAPPENED… I GOT FOOLED!

I was at the Walmart store in Clinton, Missouri shopping on December 2 (2020) and I needed some saucers for under the pots. They keep their cactus and succulents in a corner on a shelf, so I decided o go check them out. I won’t go into detail about their condition because they are usually pretty much neglected and overwatered. Anyway, I found four cacti that appeared I didn’t have in my collection. The terrible thing was that their labels just said “CACTUS”. How many times have I told myself ‘NO MORE UNLABELED PLANTS”? A label that just says “CACTUS” doesn’t count as a label. 🙂  Two I identified fairly easily, but the other two were not so easy. I thought the two were different species even though there were similarities. One was short and globular shaped and appeared to be a bluish-green, while the other was more club-shaped and darker green. Several thoughts ran through my mind like them possibly being the same species, you know, being “variable”. I really dislike that word…

The above photo shows the four cacti I brought home. I identified the one on the front right as a Gymnocalycium baldianum (Dwarf Chin Cactus) with no problem because it sort of resembled the Gymnocalycium saglionis (Giant Chin Cactus) I already had. I knew the other three were Mammillaria but I had no clue what species. I exhausted my brain looking at Mammillaria photos online, so I posted more detailed photos on a few Facebook groups for help. Within no time, a member suggested the plant on the rear right of the photo was a Mammillaria nivosa (Wooly Nipple Cactus) and another suggested the two on the left were Mammillaria hahniana. My thoughts, and reply, was “I already have a Mammillaria hahniana and it doesn’t look like those two plants.” Well, I had forgotten a few things… Mammillaria hahniana is a “variable” species… GEEZ!!!

Well, I revisited the Llifle (Encyclopedia of Living Forms Website) and looked at more photos online of Mammillaria hahniana. Of course, most of them featured their flowers and not the actual plant. But, after reading the detailed description on Llifle, I realized I had screwed up. The goal is to have more species not several plants of the same one. Once before I accidentally brought home two plants of two different species and didn’t realize it until I returned home and was taking photos. They were clearly labeled, too. But, I got over that and we are great friends now and they still joke with me about it. As I took photos and measurements of these two, however, they seemed a bit nervous. I put them on the shelf in my bedroom and put labels on the two that I found names for but not theirs. They really were getting more nervous because they knew they were Mammillaria hahniana and their new foster dad didn’t know it yet or didn’t want to face it. I think they were beginning to realize that I thought I screwed up and thought they had fooled me… Once I came to the conclusion that these two plants were indeed probably and very likely Mammillaria hahniana, I was fine with it. Fine because I now have three different plants of the same species that show how they can be variable… I just named them #2 and #3. Maybe I should give them the Spanish names dos and tres.

In the photo above, you can see this plant is very hairy with more of a dark green color and is club-shaped. The plant measured 1 3/4″ tall x 2″ wide.

From the above close-up, you can see hairs, wool, and spines. There is just a little speck of wool growing from the axils between the tubercles. Some of the “hair” is also coming from the axils but you have to get a magnifying glass to tell. The areoles on the tip of the tubercles have 1-4 very short central spines and 20-30 hair-like radial spines… Some are very short and others VERY LONG. Information on Llifle says these hair-like spines can be from 5-15 mm long which is just over 1/4″ to just over 1/2″. Some of the longer hairs on this plant are nearly 1″ long which I think are coming from the axils. Dos has more of a flat top similar to Unos…

The apex of Dos (#2) is clearly concaved with a lot of wool in the center. The areoles also have more wool around the top of the plant but seem to disappear somewhat farther down the stem (as the plant grows).

The top of cacti really fascinates me for some reason. It’s like the tubercles are arranged in a spiraling pattern… In the above photo, you can see the central spines are kind of whitish color with reddish tips.

Tres is shorter than Dos at 1 1/8″ tall but it is also 2″ in diameter. When I measure cactus I ignore the spines and focus on the body (stem) of the plant. Tres is kind of squat and globe-shaped like a pumpkin. It is kind of more bluish-green in color which can throw you off a little… The Mammillaria muehlenpfordtii in my collection is a bluish-green and AWESOME!

Tres has A LOT more and larger tufts of wool in its axils, especially around the top, and its hair is not as long.

From the top, Tres looks A LOT different than Dos. The concaved apex is barely visible from all the wool. The hair-like radial spines and axil hair give Tres a cobwebby appearance.

Once I came to the conclusion that it was definitely possible the two new Mammillaria were M. hahniana, I took all three plants to the back porch for a photoshoot. I brought Unos home from Wal-Mart on February 1, 2016, when it was just 1 7/8″ tall x 2 3/8″ wide. On October 15 (2020) when I moved the plants inside it measured 3 5/8″ tall x 3 5/8″ wide.

From the top view, Unos, Dos, and Tres look nothing alike. You can certainly tell how someone would think they are three different species. Am I sure they are all three Mammillaria hahniana? NOPE!

<<<<2021>>>>

The Mammillaria hahniana was enjoying a day in the sun on June 24 when the above photo was taken. It had a nice ring of buds…

I didn’t have to move the potted plants inside for the winter until October 28 in 2021. There wasn’t a chance of “F” in the forecast until then which was quite unusual. It had rained so its wool was kind of wet… As always, the Mammillaria hahniana did very well over the summer and grew to about 3 3/4″ tall x 3 3/4″ wide. The two smaller M. hahniana didn’t make it over the summer on the front porch… In fact, all four of the cactus I brought home from Walmart on December 2 in 2020 died…

USEFUL INFORMATION:
Family: Cactaceae
Origin: Mexico
Zones: USDA Zones 9a-11 (2- to 40° F)
Size: Small, maybe about 4-5” tall x 4” wide
Light: Sun to part shade.
Soil: Fast-draining. Potting soil amended with additional pumice and chicken grit or 50/50 potting soil and pumice.
Water: Average during the growing period, not necessary in winter.

 You can read my Cactus Talk & Update and Cactus & Succulent Tips to get my opinion about growing cacti and succulents.

When you bring your new plants home from the store, you need to check their roots and the soil to see if they are wet. If so, you may want to repot it right away. It is advisable to repot them in a better potting soil more suitable for cacti and succulents.

<<<<2022>>>>

I had to move the potted plants inside for the winter on October 16 in 2022. The Mammilaria hahniana did GREAT and grew to, ummm… Well, something is weird. I wrote down that it was 5 1/2″ tall on October 16, but I noticed when I was writing this that it was 3 3/4″ tall last October 28. I thought it was impossible it grew that much, so I measured it again on December 8. It measured 4 3/4″ tall. So, I either goofed or Mammillaria hahniana was standing on it’s toes… Either way, it did grow at least an inch taller over the summer. Oh, I put the cactus on the front porch with the succulents in 2022 so they could have a little more shade. They all did very well…

<<<<2023>>>>

Even though there was no “F” in the forecast until October 30, it was going to be a rainy week so I moved the potted plants inside on the 23rd and 24th. Time for photos and measurements… 

The Mammillaria hahniana did very well during the summer on the back porch in full sun despite the heat and drought. It measured 5 3/4” tall x 3 3/4” wide when I moved it inside for the winter. 

I really enjoy the Mammillaria hahniana and I will keep adding more photos and information as time goes by. Having three in my collection that look nothing alike will be very interesting…

I hope you enjoyed this page and maybe found it useful. I would like to hear from you if you have any comments, questions, or suggestions. 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.

FOR FURTHER READING:
PLANTS OF THE WORLD ONLINE (GENUS/SPECIES)
WIKIPEDIA (GENUS/SPECIES)
LLIFLE (ENCYCLOPEDIA OF LIVING FORMS)
DAVE’S GARDEN
CACTIGUIDE
ROYAL HORTICULTURAL SOCIETY