November 23, 2009

Cactus Monday: Leuchtenbergia principis

At the last Garden Club of Austin meeting, I picked up a funny looking plant called a Leuchtenbergia principis. It's in the cactus family and the sole species of its genus. I imagine it was difficult to place within a taxonomy due to its unusual growth habit. It looks more like an agave at a young age which might explain why it's called the "Agave Cactus." However, it blooms from the side, not through the center like agaves do. At the end of each tubercle, there are soft spines which are not dangerous at all. As the plant matures, it forms a trunk like yuccas and aloes. Scholars have speculated that it's a mammillaria, a cycad, an aloe, a ferocactus, and probably some other possibilities that I haven't come across, so it's no wonder it was put in the cactus family and given its own genus. Apparently, it has been in and out of botanical fashion over the past 160 years since its "discovery" in 1848. It's hardy to around 20F and native to Central and Northern parts of Mexico.

During the meeting, a gentleman presented a slide show of his latest visit to the Sonora Desert, and he kept talking about "nurseries". However, these nurseries weren't places to buy plants - they were plants in nature that gave shelter to young cacti. I'd never heard of that term although I've been warned to keep young cacti out of full blazing sun. I imagine the leuchtenbergia does best with a plant "nurse" as it is a very slow growing cactus, and apparently the plant looks better in cultivation than in habitat which is true of many succulents.

Speaking of succulents, I had a friend ask me what was the difference between succulents, cacti, and agaves, and honestly, it stumped me. I ended up looking it up. Succulents come in 3 forms: stem, leaf, and caudiciform. A stem succulent stores its water mostly in its stems such as with cactus whose spines are modified leaves. A leaf succulent stores its water mostly in its, DRUM ROLL, leaves such as with agaves and aloes. Caudiciforms make their own specialty group within succulents. The most common caudiciform that I've seen is the desert rose. All cacti are succulents, but not all succulents are cacti. I hope I got all that right.

Taxonomy is a wondrous thing.

To participate in Cactus Monday, go to Teri's Painted Daisies.


  1. Wow, what an interesting plant. You really researched this well.

    Good to see you back.


  2. Wonderful post. And what an unusual plant.

    HCM, Evelyn

  3. You have an indepth knowledge of cacti...The facts you've presented are really interesting.

    Even I had this doubt abt succulents n cacti...Thanks for sharing this info:)


    ps:Thanks for visiting my blog:)

  4. A wonderful post! It is true that the young cacti in the desert often grow up under a tree giving it protection. I love that cacti-I have something similar but not quite the same.

  5. Boy, I would have sworn this was an aloe plant on first glance! Succulenbts are an amazing group of plants...many confusing and "drive you crazy" with finding proper names!
    Happy late Cactus Monday!


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