A plant I really wish I could reliably grow here in my garden is Pachycormus discolor, commonly known as elephant tree, but not to be mixed up with the other elephant trees in the genus Bursera. (Yes, it’s confusing, and this is why we use Latin names over common ones in science.) Found only on the Baja Peninsula, Pachycormus discolor has a thick trunk with white bark that peels back to reveal greenish patches and spongy wood that stores water for the long dry spells that they face in habitat. Trees are generally up to 20 feet tall (6 meters) and are extraordinarily slow-growing – many photos of individual trees taken 50 or more years ago and compared with more recent photos of the same plants show virtually no change in size, leading to potential age estimates of 1000 years or more.

Pachycormus discolor and Ferocactus gracilis combine wonderfully in central Baja California, alongside Agave cerulata, Cylindropuntia alcahes, and Fouquieria columnaris. You figure out which is which.

Seedlings that are well-watered can develop fairly rapidly, and the Desert Botanical Garden in Phoenix has a nice one that is probably about 85 years old that isn’t a lot smaller than these ones shown here, although they aren’t as thick and gnarled by the rigors of lengthy drought on lava fields that the wild ones in Baja are. So they don’t necessarily have to be quite as slow in captivity.

Baja fire barrels (Ferocactus gracilis) show off their fiery red spines against the ghostly pale trunk of elephant tree (Pachycormus discolor). It is normal for the barrel cactus spines to darken with age towards the bases of the plants, although it’s not the most attractive feature once it happens.

These plants are not very frost-tolerant, which is why they are seldom grown in US landscapes, although they can survive reasonably well outdoors in coastal southern California and Phoenix, Arizona. Well, at least I can grow many of their companion plants, inclduing the red-spined fire barrel cactus (Ferocactus gracilis), bluish-white Agave cerulata, and the ever-charismatic boojum tree (Fouquieria columnaris). Baja plants are among the best succulents imaginable.

The green, photosynthetic cambium layer of the elephant tree helps manufacture some of the food for the tree in the trunk and branches, even when leaves are absent, which they quite commonly are in this arid region of Mexico. The pale outermost layer of dead bark cells reflects hot desert sun, helping keep the trunk cooler and reducing water loss, while permitting some light to penetrate for photosynthesis. It’s a remarkable adaptation to the rigors of this climate, although a price of extremely slow growth is paid by the trees.