Updated: Oct 18, 2021
Frequently, I second guess myself on the scientific name of this deciduous tree. Pistache, pistachio...isn't there an "h" in the genus? It is part of the reason why I am posting about it now, so I do not have to look it up ever again. My tripping up is simultaneously due to its common name and its association with the pistachio nut, which, and this is important, is not this species. Pistachio, or Pistacia vera, produces the famed nut and thrives in California's hot inland valleys, but our subject tree, Chinese pistache, or Pistacia chinensis, only produces a small drupe that at best has decorative value and is inedible. Well, at least not for humans, but birds might enjoy them, broadcasting the seeds everywhere. Thankfully, P. chinensis has not become invasive in California but is apparently a problem in Texas. California's problem is a little different.
Chinese pistache's popularity led to over planting in the City of San José, prompting the City Arborist to all but band its planting in public spaces such as for street trees. I know this because of my work for the City where (day job) I review plans and direct developers to not plant the tree on public streets. There are exceptions, of course, but our department follows the 10-20-30 rule for selections of trees, where we strive to plant 10% of any one species, such as Pistacia chinensis, but also allow up to 20% of any genus, meaning we could also plant Pistacia vera or Pistacia lentiscus (not that we would or should), and more broadly, plant 30% of any one family (which may hold multiple genera). For our example, we would strive to plant no more than 30% of genera within the family Anacardiaceae, or the cashew family, to which Pistacia belongs. In total, there are 83 genera currently listed for this family.
Monitoring the inventory is challenging and expensive, nor will a public inventory take into consideration how many trees are planted on private property. As a plan reviewer, however, I observe on a regular basis landscape architects specifying P. chinensis and at least two other species: Lagerstroemia indica and Platanus x hispanica. Currently, we only allow their planting to infill along streets between established trees of the same species. Otherwise, we strive for introducing more underrepresented species for ecological diversity and the minimization of monocultures. This is a long-winded explanation to encourage designers to check with their local municipal arborist for acceptable species for their projects' public spaces.
Time to shift gears back to our subject tree, P. chinensis. Its popularity is due to its beautiful form (excellent shade tree), hardiness, and truly stunning fall color. This latter benefit is key for California. While other trees, such as the famed red maple, Acer rubrum, are known for their brilliant fall color (think of New England's annual autumn displays), P. chinensis can hold its color without fading during our Diablo or Santa Ana Winds (depending on where you are in the state). Acer rubrum's fall color will wither in arid heat, so the next go-to fall color tree is our subject pistache. Unfortunately, there is another problem.
A general online search for keywords "pistache, limb, break," will generate multiple sites addressing this challenge, or at least reactions to it. While the trees are known for their strong branch strength, if they are not well structured in their early growth they can become unsound. As most structurally weak trees mature, the added weight may lead to limb breakage, something we have often seen in the public sector. Nurseries, especially high-volume growers, typically do not structurally prune saplings. This means that when trees are released to contractors for planting, its "hit or miss" if landscapers and/or arborists will perform corrective pruning in the field to avoid damage later in life. This is a general rule, young trees should be inspected and receive corrective pruning by a skillful technician, usually an arborist, in an attempt to minimize future vulnerability to breakage. Does this happen? More often the answer is no; the consequence comes years later when trees break, such as in a wind storm when foliage is fully flushed causing a wind sail effect. Does this happen often? Not enough to stop planting, particularly if the chains of command (mainly designers and contractors) insure tree inspections and make necessary corrections.
I have outlined the pros and cons for using pistache in landscape designs. The problems here are representative of what can happen with any tree that 1) becomes too popular in a particular community or region, leading to 2) over planting, monocultures, and what I did not discuss, infestation vulnerabilities causing species specific risks; and finally, 3) why early inspection and corrective pruning can change the fate and future of trees for long-term performance. I have not even talked about the fruit drop of this tree, which if not collected for floriculture projects, will become an annual clean-up task. Designers have other options, such as the fruitless Pistacia chinensis 'Keith Davey', or make sure to select male species in autumn months when their gender can be verified. Should we stop planting pistache? No, it is a beautiful and useful tree. However, this post should help young designers understand the pitfalls of specifying the same plants over and over again, as the impact can be long-term.
West Valley College Campus Location: Pistacia chinensis
Off campus, on Fruitvale Avenue median
Long: 122° 0'49.84"W
Fall leaf color photos upcoming.
Botanical Name: Pistacia chinensis
Pistacia: Greek, pistakia, for pistachio tree
Chinensis: Associated with China
Common Name: Chinese pistache
Family Name: Anacardiaceae
Positioning: Background, feature
Garden Themes: Woodland, children's, autumn/winter
Uses: Shade, street tree, commercial, park/open space, specimen, accent, lawn, bosque
Type: Deciduous tree
Form: Round, oval, vase
Size: 40' tall by 30' wide
Outstanding Feature(s): Fall color; decorative fruit
Bark: Dark brown to light gray becoming furrowed or scaly with age
Type: Odd pinnately compound
Shape: Leaflets: Lanceolate
Color: Dark to medium green turning yellow, orange, and/or red in autumn
Surface: Glabrous, glossy
Flower: Spring. Yellow-green panicles, small, inconspicuous
Fruit: Autumn. Clusters of drupes persist on tree, starting green turning red then blue when ripe.
cultural requirements, tolerances & problems
Sunset Zones: 4-16, 17 (warm locations), 18-23
USDA Zones: 6-9
Light: Full sun
WUCOLS SF Bay Area Hydro Zone: Low
Texture: Sand, loam, clay if well composted
Moisture Retention: Well-drained. Accepts periods of dryness.
pH: Slightly acidic to highly alkaline
Tolerances: Drought, deer
Problems: Fruit drop may be messy if not used for decorative purposes
Branch Strength: Strong
Insects: Not recorded at time of posting
Disease: Root rot, verticillium
citations & attributions
Bayton, R. (2019). The Royal Horticultural Society's the Gardener's Botanical: An Encyclopedia of Latin Plant Names. London: Mitchell Beazley.
Extension Gardener. "Pistacia chinensis." North Carolina State University, Raleigh. Accessed on September 25, 2021, from https://plants.ces.ncsu.edu/plants/pistacia-chinensis/.
Norris Brenzel, K. (Ed.). (2012). The New Sunset Western Garden Book. New York: Time Home Entertainment, Inc.
Plant Finder. "Pistacia chinensis." Missouri Botanical Garden, St. Louis. Accessed on September 25, 2021, from https://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?kempercode=b641.
SelecTree. UFEI. "Pistacia chinensis Tree Record." 1995-2021. Cal Poly State University, San Luis Obispo. Accessed on September 25, 2021, from https://selectree.calpoly.edu/tree-detail/1086.
IFAS Extension. "Pistacia chinensis: Chinese pistache." University of Florida, Gainesville. Accessed on September 25, 2021, from https://edis.ifas.ufl.edu/publication/ST482.
Water Use Classification of Landscape Species. "WUCOLS IV Plant List." University of California, Division of Agriculture and Natural Resources, Davis. Accessed on June 28, 2021.
All photos by TELCS.