Mammillaria vetula subsp. gracilis (Syn. M. gracilis var. fragilis)-Thimble Cactus

Mammillaria vetula subsp. gracilis (Thimble Cactus) after I brought it home on 4-20-13, #144-7.

Thimble Cactus

Mammillaria vetula subsp. gracilis

mam-mil-AR-ee-uh VET-uh-luh GRASS-il-is


Mammillaria gracilis var. fragilis

mam-mil-AR-ee-uh GRASS-il-is FRAJ-ih-liss

I brought this Thimble Cactus home with me from Lowe’s on April 20, 2013. The label said it was a Mammillaria gracilis fragilis… Upon research, I found out that name had changed.

Mammillaria vetula subsp. gracilis (Pfeiff.) D.R.Hunt is the correct and accepted infraspecific name for this cactus. It was named and described by David Richard Hunt in Mammillaria Postscripts in 1997. It was first named Mammillaria gracilis Pfeiff. by Ludwig Karl Georg Pfeiffer in Gartenzeitung in 1838.

Mammillaria gracilis var. fragilis A.Berger was named and described by Alwin Berger in Kakteen in 1929.

Mammillaria vetula Mart. was named and described by Carl (Karl) Friedrich Philipp von Martius in Nova Acta Physico in 1832.

There are other synonyms in a roundabout way, one way or another, but you can check out the links below for more about them.

Plants of the World Online says Mammillaria vetula subsp. gracilis is a synonym of Mammillaria vetula. OK, so I goofed on purpose. Well, Plants of the World Online is a fairly new site and they are still uploading data. Perhaps they haven’t figured out that Mammillaria vetula subsp. gracilis should be an infraspecific name. It is accepted on Llifle, Dave’s Garden, and CactusGuide…


Mammillaria vetula subsp. gracilis on 6-1-13, #151-52.

This was my first Mammillaria so I was anxious to see how we got along. When temps warmed up enough I moved this cactus outside with the rest of the plants then I put it in a larger pot.


Mammillaria vetula subsp. gracilis on 7-30-13, 165-43.


Family: Cactaceae
Origin: Mexico
Zones: USDA Zones 9a-11 (20 to° F)
Size: 6” or so tall
Light: Sun to part shade
Soil: Fast-draining. Potting soil amended with extra grit and pumice or perlite
Water: Average during the growing period, barely in winter
Flowers: Pale to bright yellow


Mammillaria vetula subsp. gracilis on 8-23-13, #178-62.

The Thimble Cactus is a very easy plant to grow if you follow a few simple rules. They don’t mind regular watering during the summer months, but to much water in the winter is NOT a good idea. They wouldn’t mind if they didn’t get any. When I water my cactus and succulents during the summer, I just go over them with the wand one time. The other plant’s pots get filled to the rim.


Mammillaria vetula subsp. gracilis on 9-17-13, #188-44.

Information online says that this plant does well in full sun to part shade. When you move your plants outside for the summer, they need to get used to more light gradually. I normally place mine in light to part shade at first then gradually slide them over on the table to get more light. If they show any sign of burn, I put them back in more shade. I think I kept this cactus on the table behind the shed in more shade all summer.


Mammillaria vetula subsp. gracilis from the top on 9-30-13, #192-6.

Once in a while I will notice one of the balls of thorns has fallen off on the table. I just put it back in the pot where it can take root. That is actually how they spread in the wild.


Mammillaria vetula subsp. gracilis on 6-1-14, #228-59.

We made it through the 2013-2014 winter just fine and it was glad to be back outside again.


Mammillaria vetula subsp. gracilis on 7-12-14, #231-70.

I really enjoyed this plant as a companion, but unfortunately, I gave up most of my plants after the above photo was taken. I am back collecting plants again, so maybe someday I will bring home another Mammillaria vetula subsp. gracilis.


Mammillaria vetula subsp. gracilis on 9-13-18, #507-22.

I found this cactus at Wagler’s Greenhouse when I took plants there in September. It was unlabeled but I was sure it was a Mammillaria. I wasn’t sure of the species so I had to do a little research. After a while, I decided I better get some help from the Mammillaria Group on Facebook. A member promptly replied that it was a Mammillaria gracilis var. fragilis and another said it was a Thimble Cactus. Well, to me, this plant didn’t look like what they said.


Mammillaria vetula subsp. gracilis on 10-10-18, #519-53.

I had to move the potted plants inside for the winter on October 10 because the forecast was calling for an “F” in a few days and the nighttime temperatures were getting cooler. I usually measure the cactus and succulents when I bring them inside. This plant measured 2 1/4″ tall.

A few weeks ago I posted a more recent photo and I received the same answer. This time, I corrected the member and told him that Mammillaria gracilis var. fragilis was a synonym of Mammillaria vetula subsp. gracilis. Ummm… He didn’t answer back or even click “like”. 🙂 I think I need to stop doing that.

I supposed it was possible and even probable this plant could be a Mammillaria vetula subsp. gracilis so I went ahead and changed the captions on its previous photos. They were labeled “Unknown Cactus”.


Mammillaria vetula subsp. gracilis on 11-29-18, #534-30.

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


Mammillaria vetula subsp. gracilis close-up on 12-1-18, #535-22.

The species, Mammillaria vetula, has 1-2 central spines and at least 25 radial spines. The subspecies often lacks the central spines and only has 11-16 radial spines. BUT… This plant is 2 1/4″ tall! Plus it is growing offsets from the stem instead of from the bottom so how could it be a Thimble Cactus? But guess what? I looked at the old photos of the Mammillaria vetula subsp. gracilis from 2014 and it was doing the same exact thing… So, I guess that settles it.

The new one is definitely going to be interesting to watch grow…

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. They take you directly to information about the species.


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