In the past decade, Chilopsis linearis has started to pop up in Northern California as a viable, colorful option in the landscape (their tubular flowers are very showy)! Maybe it has been around longer than I have noticed, but I am certainly taking note now. I even planted one in the garden to remind me of its beautiful form and character. Native to Southern California and the American Southwest means it is "fire ready." The United States Department of Agriculture's Forest Service has observed its response to fire, noting their above ground destruction but ability to regenerate. Durable.
In San José, a portion of Charlotte Drive is lined with them exhibiting mixed results. While a number of trees appear to be thriving, gaining a size worthy of being called street trees, several were not so successful and have been replaced. My own experiment is not finished. Planted last year, it has not grown, as Sunset describes, "3 ft. per year, then slows, eventually developing shaggy bark and twisting trunks" (p. 239). That would be amazing, but I think ours is competing for water with the more mature street tree next to it. Slow growth happens with some trees and shrubs, where their first year(s) might lag before taking off, so I am choosing to be patient.
Using desert willows, also known as desert catalpas, as street trees has other challenges. Their natural habit is multi-trunk, despite nurseries sometimes selling them as standards. As multis, limbs might go every which way, including into the streets or sidewalks signaling a need to prune them for clearances. Over time, their form can be attractive. This is the nature of multi-trunk plants, they need regular corrective pruning if a specific shape is required by the design, which for C. linearis, lends itself to positions in private gardens or places where their growth will not be restricted.
Cultivars offer a small range of colors, from the magenta as shown to lavender or a tow tone mix of white and purple (also shown). Apparently fragrant, I have yet to experience their scent. Desert willow's long bloom cycle during the warm season also lends to their attractiveness, but once the blooms are finished, well, looks can be deceiving. Long, narrow seed pods form and are prolific. From a distance, the seedpods look like longer leaves while they are green, and this is the problem. Once they mature from green to reddish brown to tan, at the same time dropping leaves in autumn, suddenly the tree looks like it is about to die (see limb detail below). The pods linger through winter, making their unsightliness all that more discouraging. If people can turn the other way until the first blooms, then all will be forgotten!
West Valley College Campus Location: Chilopsis linearis
Student Services (westerly landscape area)
Lat: 37°15'50.35"N
Long: 122° 0'43.53"W
facts
Botanical Name: Chilopsis linearis
Chilopsis: Greek, cheilos for lip; opsis for resembling, which is a great way to describe the flower.
Linearis: Having narrow leaves.
Common Name: Desert willow; desert catalpa; mimbre
Family Name: Bignoniaceae
Origin: Native, Southern California deserts, Southwest deserts to Mexico along seasonal washes at 5,000' elevations
design considerations
Positioning: Background, street, embankments
Garden Themes: Mediterranean/dry, sub-tropical, rock, residential, pollinator, hummingbird
Uses: Street (standard) and medians, specimen, planter/container (multi), informal screen
identifying characteristics
Type: Deciduous shrub (multi-trunk) or tree (multi or standard)
Form: Round, spreading, arching
Texture: Fine
Size: 30' tall (standard) by 20' wide
Outstanding Feature(s): Flower
Bark: Light green when young turning light gray and exfoliating
Leaf:
Type: Simple
Arrangement: Alternate
Shape: Linear
Margin: Entire
Color: Medium to light green with no apparent fall color
Surface: Glabrous
Flower: Spring to autumn. Terminal clusters of trumpet flowers in white, magenta, purple, lavender, or two town.
Fruit: Autumn to winter. Large, linear capsules green when young turning tan when ripe
cultural requirements, tolerances & problems
Sunset Zones: 3B, 7-14, 18-23
USDA Zones: 8-10
Light: Sun
WUCOLS SF Bay Area Hydro Zone: Moderate
Soil:
Texture: Rocky, sand, loam
Moisture Retention: Well-drained
pH: Neutral to very alkaline
Tolerances: Deer, Texas root rot
Problems: Persistent seed pods
Branch Strength: Medium
Insects: Not observed at time of posting.
Disease: Root rot
citations & attributions
Calscape. "Desert Willow." California Native Plant Society, Sacramento. Accessed on August 22, 2021, from https://calscape.org/Chilopsis-linearis-(Desert-Willow).
Fire Effects Information System. "Species: Chilopsis linearis." United States Department of Agriculture, Forestry Service, Washington D.C. Accessed on August 22, 2021, from https://www.fs.fed.us/database/feis/plants/shrub/chilin/all.html.
Norris Brenzel, K. (Ed.). (2012). The New Sunset Western Garden Book. New York: Time Home Entertainment, Inc.
Plant Finder. "Chilopsis linearis var. linearis." Missouri Botanical Garden, St. Louis. Accessed on August 22, 2021, from https://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?taxonid=277913&isprofile=0&.
The Real Dirt Blog. "The Desert Willow: A Beautiful Small Tree for Native Gardens." University of California Master Gardeners, Butte County. Accessed on August 22, 2021, from https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=43347.
SelecTree. UFEI. "Chilopsis linearis Tree Record." 1995-2021. Cal Poly State University, San Luis Obispo. Accessed on Aug 23, 2021, from https://selectree.calpoly.edu/tree-detail/345.
Taxon Report. "Chilopsis linearis." Calflora, Berkeley. Accessed on August 22, 2021, from https://www.calflora.org/app/taxon?crn=9803.
Water Use Classification of Landscape Species. "WUCOLS IV Plant List." University of California, Division of Agriculture and Natural Resources, Davis. Accessed on July 27, 2021.
Photos:
All photos by TELCS.