Caudiciforms: Botanical Camels

Posted at 11:57 am June 4, 2007 by Seth Menser

 cabbage on a stickCamels, like all creatures, need nutrients to survive. But in the desert, food and water are scarce. So how is it that camels can survive in a harsh climate? They store fat in their humps and live off it in tough times. Certain unique plants and trees from desert or seasonal rainy regions have adapted ways of storing much-needed water in their trunks, and we call these plants caudiciforms. They can come in all sorts of shapes and sizes and belong to a wide range of plant families. One exciting characteristic of these plants is that their trunks, branches, and bases tend to be swollen, which helps the plant out in times of drought, but also makes odd-looking plant specimens that people collect and treasure.

Succulent plants also have ways of storing water, but what sets them apart from caudiciforms is that succulents store water in their thick, green leaves, while caudiciforms store it in their caudex, or base, which is not green and does not produce chlorophyll. On most caudiciforms, the foliage is usually small and brittle. This is because, in times of drought, many caudiciforms will become dormant, drop their leaves, and live off stored water reserves. In these times, the plant’s main goal is to make it through the dry period, so little energy is spent on producing vegetative growth. When the rains return, the plant is happy and produces a mass of greenery and flowers freely, while also storing up water for future dry spells.

Probably the most famous of all caudiciforms is the ponytail palm Nolina recurvata, formally known as Beaucarnea recurvata. Ponytail palms come from southeastern Mexico and are grown all over the world as house plants. They look a lot like palms, but they’re not: they are in their own family. In climates like ours, they can be grown outside and get to be very large. Here at the San Diego Zoo, we are lucky enough to have at least 60 ponytail palms on grounds, and some very old specimens measure over six feet across at the caudex (base)! In our Madagascar Garden, one can find an assortment of caudiciforms being grown, as Madagascar is home to a large number of these exotic plants. Hawaii is also home to a few of them, and in our Hawaiian Native Plant Garden, a grouping of the cabbage on a stick Brighamia insignis (pictured above) can be seen growing among lava rocks.

While many caudiciform plants are grown all around the Zoo, the Horticulture Department has a display box at the north end of Horn & Hoof Mesa filled with some exotic, caudex-forming plants. Next time you visit the Zoo, stop by the camels, but also keep your eyes out for the camels of the botanical world, caudiciform plants.

Seth Menser is a gardener at the San Diego Zoo.

Read Seth’s previous blog, New Browse Hill.

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11 Responses to “Caudiciforms: Botanical Camels”

  1. Shirley Sykes says:

    Hi Seth. I’m becoming more and more interested in the zoo’s spectacular collection of plants from around the world. On days when the animals are hiding, sleeping, or otherwise inactive, I try to focus on the plants more intently. Where in the zoo are some of the ponytail palms located? I’d like to seek them out, especially the old specimens. Thanks for all the information

  2. Margaret says:

    Thanks, Seth, for a fascintating education in caudiciforms. I have a BS in Horticulture from Univ of Connecticut. Since we were located in the Northeast, which it is not an arid climate, I don’t recall studying caudiciforms in particular, so I am glad to have read about them. I do remember Pony Tail palms from my days in the greenhouses though.

    Just like animals, plants have had to adapt to their surroundings to survive. It is truly amazing to see the diversity. I read about the world’s ” ugliest” plant the other day that survives on the Western side of the desert by the sea. It has only two leaves which curl up into an ” ugly” mass over 10 feet long. It takes in the ocean mist as its water source to survive in an area that very rarely gets rain. Like many animals, it is on the verge of extinction, and may already be extinct in the wild.

  3. Cheryle O'Donnell says:

    Dear Seth Menser,

    I am finishing up my dissertation at the University of Cal. Davis and have found that I need some information on a tree from which I collected thrips. The tree is located in the botanical gardens across the street from the SD Zoo’s main entrance . It is near the main drive. I documented the collection information in two forms and both were partially distroyed. I was wondering if you could provide some additional information? The tree has grey-green leaves, similar to an Acacia from what I can remember. My label reads ‘Dor… rodindifolium’. I believe the tree had yellow flowers as well. Can you provide a bit more information on the botanical name? If not I appreciate the effort.

    Thank you,

    Cheryle O’Donnell

  4. Seth Menser says:

    Thanks for all the responses. Shirley, check outside the Zoo, on the entrance plaza next to the restrooms, for a extremely large ponytail palm. This specimen is decades old and is at least 6-7 feet across at the soil line. Inside look for several near the addax exhibit. We do have a good stockpile of these plants in our nursery for a future project. Our Horticulturist is fond of this plant and has plans to create a grove of ponytail palms with a path going through them, so we can look forward to that.

    Cheryle, I will look for that tree. I can’t picture it right now, but from your description it could be an Acacia, they tend to have yellow flowers. Check back in a few days and I’ll have the name for you.


  5. Seth Menser says:


    I believe that the tree you are trying to ID is a Mexican palo verde Parkinsonia aculeata. There are a few of them in that area. There is also a sweet thorn acacia Acacia karroo nearby. I hope this helps.


  6. Amy Ames says:

    Hi Seth,

    Your blog entries remind me of my husband. He is a botanist, currently persuing a PhD in genetics. We will be bringing our 3 young children to the San Diego Zoo for the first time next week. I am sorry to say that we will be missing your monthly walk through of the orchid greenhouses. My husband is an orchid fanatic currently specializing in phaleonopsis species, and I was wondering if there was a way that the greenhouses could be viewed while we are there, or if you even allow for special visits? Regardless of what is possible, you can be assured that he will spend all of his time checking out the plants and and not nearly so much looking at the animals.

  7. Amy Ames says:

    Our Brighamia insignis that we have in our window looks pitiful. My husband hasn’t grown it before. Do you have any suggestions? It’s dropping some leaves and looks a bit chlorotic.

  8. Seth Menser says:


    The biggest killer of these plants, besides hard frost, is over-watering. If he’s not over-watering it, try to use filtered water instead of tap water. Right when you enter the Zoo, on the left side are self-guided botanical guides to many of our prized plant specimens. I hope you enjoy our wonderful Zoo.


  9. Stanley Chung says:

    Mr. Menser,

    We are looking for some information regarding one of the massive palm trees we saw at the zoo. My family and I went to the San Diego Zoo about two years ago and we saw a palm tree that we want to possible cultivate in our home. We think it was a ‘Thai Palm’. It was very very tall.

    Any info would be very much appreciated.


  10. Seth Menser says:


    The palm that your talking about is called a Giant Fishtail Palm Caryota gigas. There are several of them planted around the Zoo. The biggest is down by the hornbills in Cat Canyon.


  11. Kathryn says:

    I have a ponytail palm that Ive had for almost 30 years in my front yard. It has bloomed every year for several years and has seemed happy, however this year I’ve noticed that the trunk seems to be splitting. It branched into 4 stems about 2 feet off the ground 20 years ago, and the split goes between them. Does this plant divide in this way? The split appears clean and dry, but as it is only about an inch wide I cant really tell. I’ve enjoyed viewing your large ponytail palm for years and hope you can help with mine.
    Thank you for your wonderful site, it has been very informative. .

    Thanks again,

    Seth responds: As ponytail palms get older, they tend to split and form cavities and have many odd-looking features. It gives them character! I have observed this on several decades-old specimens. So I would not worry. But, if it does get worse and worse and it looks like it is rotting, then you have a problem. I would just keep an eye on it, and if you can keep rain water, or any water for that matter, out of the split, that would be helpful. It should repair itself, and your “prized” tree should be in good shape for years to come. Ponytail palms are true survivors! Thanks for your interest in our horticulture elements here at the Zoo.