What is the caudex of a plant ?

Ah, the caudex plants ! Baobabs, Euphorbias, Dracaenas, Desert Roses… Many of the most popular exotic plants fall into this category. With their spectacular silhouette, diversity of sizes and foliage, each of them is unique!

We tell you more.

What is a caudex ?

Spectacular caudex of an Adenium obesum

The caudex of a plant is an organ that is part of its trunk, stem or root system, capable of storing water. This water is stored in the form of nourishing juices. It is this accumulation of juices that causes the swelling of the succulent part of the plant. The water is obviously captured by the precipitations, but can also come from the dew and the morning fogs.

What is the purpose of a caudex?

These reserves of juices enable the succulent plant to survive periods of drought. These droughts can be due to a lack of rainfall, but also to a very permeable soil that dries out quickly, or even to a salt-rich environment. In parallel, caudex plants often develop a means of combating water evaporation and intense heat, with very limited foliage, present only for short periods of the year, or non-existent altogether.

The different types of caudex?

Caudiciform Plants

Caudiciform plants have a caudex at the base of the plant, which may be round or flattened and touch the ground; it can then be mistaken for a pebble or cobble.

They emit thin, non-woody stems, and are also known as brevicaul plants, i.e. with short stems.

It often resemble a carapace, a hollowed-out breastplate.

Spectaular caudex of a dioscorea elephantipes
Caudex of a Tortoise plant
Close up on the caudex of a Caudiciform Plant

Caudiciform Plants are mainly desert plants, which receive a significant amount of water over a short period, and store it to survive the droughts of the rest of the year. They grow for only a few months of the year, then go dormant until the next rains.
For pot cultivation, watering should therefore be stopped as soon as they lose their stems, leaving them dormant until new leaves appear, when watering should be resumed.

This caudiciform family includes Dioscorea elephantipes, Bowiea volubilis, Cyphostemma juttae, certain Euphorbias

Pachycaul plants

Two specimens of Adenium obsesums with huge caudex
white floss-silk tree and its enormous caudex
boojum tree in the desrt

Pachycaul plants have a thickened lower part to their main stem, while the top will bear spindly woody stems and leaves during the wet season, which they will lose during the dry season and become dormant.

Their caudex can be spectacular !

Unlike caudiciform plants, therefore, they have very thick, pot-bellied trunks, most of them in the shape of a bottle or an elephant’s foot; it’s this swollen part of the trunk that holds the water.

They can evolve into large trees with spe, as in the case of the Baobab.

adansoniadigitata

This family of  plants includes Jatropha podagrica, Pachypodium, Adenium obesum, Chorisias, Tylecodons, Brachychitons, Dracaenas, Hawaiian palms

Hybrid caudex forms

We humans like to create categories and fit living things neatly into them. But nature has no use for our categories, and is far more imaginative!

So, not everything is so simple, and some caudex plants are difficult to classify. Take Fockea multiflora, for example: its caudex would be classed as a caudiciform plant, yet it emits woody stems that are characteristic of pachycaul plants !

The fact remains that we’ll never tire of plant diversity, caudex or no caudex, caudiciform or false caudiciform!