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  • Writer's pictureChristian Aguilar

Psorothamnus spinosus - Smoke tree.

This small tree/big shrub reminds me of the times I traveled through the whole Baja California Peninsula highway, to visit my family down there. I remember watching them from the car, in the section between San Felipe, Baja California and Coco's Corner, and I always wondered if the trees looked grey because they were all covered in dirt haha, but it turns out that's the way they are, and that's why we call them smoke tree or palo cenizo in Spanish.

Smoke tree in a front yard in the neighborhood Tanque Verde, Tucson, AZ, US.

Living here in Tucson, I came across this tree once again, it was being sold at one of the few native plant nurseries in the Sonoran Desert, Spadefoot Nursery. I bought one with a lot of enthusiasm and nostalgia, since having plants from Baja California in my patio makes me feel close to home. And to my bad luck (by my own stupidity) I killed it, because I put it in a shady space, since I don't have much space in my patio due to having so many plants now. This tree likes the sun, direct, and for several hours, like almost all the plants of the Sonoran Desert.


The Smoke tree consists of spiky branches, not so many leaves and small, beautiful and aromatic purple flowers that appear between May and July.

The bees feast on the nectar of the flowers.

Not long ago I was in the car heading to my office and from the corner of my eye I saw a tree completely covered with purple flowers in front of a house, I decided to go back to see what tree it was, and it was a smoke tree. I parked and got out to take some photos and the pleasant aroma that those flowers give off was shocking. What a beauty!

Smoke tree is a perennial legume tree or shrub, its seeds come in pods, usually each pod has between 1 and 2 seeds. Its branches end in sharp points, so it is not recommended to plant it in places with high traffic because it will sting you. It can grow up to 16 ft high and 10 ft wide. When you find it in its natural landscape, you will realize that it likes to be in streams, or in rocky places where there is sometimes water. In order to germinate the seeds, you have to imitate nature, in general the seeds fall on those rocky-sandy areas and are scratched, run with the water when it rains and hit between the rocks. If you find seeds of this tree, put them in water for 24 hours, then sand the bark a little and soak it again and then put it in moist soil.

This tree or shrub looks like an ash cloud, its color stands out when planted near a dark wall, or in front of several plants with bright green leaves. It is an accent plant, it is not a tree that provides great shade, if you have a large space in your patio, where it gets direct sun, plant this tree there, particularly in a space where people will see it and appreciate its color and aroma. Smoke tree is home to the Hemileuca burnsi moth.


Type: Small perennial tree or large shrub.

Size: Up to 16 ft high and 10 ft wide.

Water use: Once established, it survives with rainwater, although it is good to water it in the hottest days of the summer.

Flower season: May to July.

Flowers: Small, purple with a few yellow dots.

Food for: Pollinators. Native bees, hummingbirds, butterflies and others feed on the nectar of its flowers. Its seeds are food for some mammals and birds.

Where to plant: Full sun, good drainage.

Distribution: Sonora, Baja California Norte, Arizona, California and Nevada.

Ancestral use: I read somewhere that its new branches serve as food, also the seeds.

Landscape design: It is an accent plant, which means that it is a plant that attracts a lot of attention for its beauty and originality. Planted in front of a dark wall, or several green plants, the smoke tree always stands out for its grayish color and when it blooms it is an explosion of purple color and delicious aroma. It is recommended to put it in a place away from busy areas, since its branches are very pointy. They can serve as a barrier, combined with other large shrubs, to give a sense of privacy and protection in a patio. It does not do well in pots, as its roots need room to grow, and they love sun and warmth, but they do not tolerate temperatures below 20°F.

Click in the right arrow to see more photos...


Sources

Books:

  • Baja California Plant Field Guide 3rd Edition, Norman C. Roberts and J. Rebman.

  • Native Plants for Southwestern Landscapes, by Judy Mielke. University of Texas Press, 1993.

Web:

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