Camels, 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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