When thinking about street trees for California, there are few evergreen examples that check off all the boxes of requirements and still be compatible with an urban environment. Our own native evergreen, Quercus agrifolia, is most desirable but challenges spatial limitations, and acorns on sidewalks can lead to slips like stepping on marbles. Magnolia grandiflora, with all its fragrant Southern charm, needs more water than most urban environments can provide from our drought stricken state. There are others for certain, too many to list here when we have a real charmer for this post, Arbutus 'Marina'.
Tolerant of both drought and urban landscapes, A. 'Marina' is an evergreen with dynamic interest. The leaves are a clean, lush green, beautifully contrasting its smooth red bark, similar to our own manzanitas, Arctostaphylos, or madrone, Arbutus menziesii. Its compatibility allows this Mediterranean tree to blend well with our California natives. Unlike its cousin, A. unedo 'Compacta', a typically multi-trunked large shrub, A. 'Marina' stands on a very erect trunk with its dense canopy overhead. Available from nurseries as a multi-trunk, too, and its coloring enhances and blends within California/Mediterranean gardens. For street trees, the standard form is a reliable fixture for the urban landscape.
What I enjoy most is the flowering and subsequent fruit. Clusters of bell or urn-shaped pink flowers, small as they are, give the tree a delicate counterbalance to its dense form. Here is another added value, they flower nearly all year-round, even in winter when we need a little color. Now we can understand its common name, strawberry tree, for the fruit vaguely resembles a strawberry by look (if you squint your eyes) and flavor. Each fruit starts green and as they mature turn yellow, then orange, and when finally ripe, bright red. My own tree rarely has ripe fruit, simply because I cannot allow it to linger when I can just as easily eat them while I garden. And that's the thing...here's an opportunity to provide fruit to the public without overcommitting to oranges, apples, or pears that create so many other challenges...the need for water and regular maintenance being two. The strawberry tree offers a small fruit without the need of excessive water or care.
Like any plant, A. 'Marina' does have challenges. In 2019, the Marin Independent Journal's correspondent, Barbara Robertson, featured the University of California, Marin Master Gardeners, challenged to answer what pest and disease are currently attacking strawberry trees. A follow-up search in the University of California's Integrated Pest Management website illustrates a considerable list of pests and diseases, including aphids that excrete a sticky residue leading to sooty mold, and Sudden Oak Death, another disease attacking our madrones. As strawberry trees have become popular in public and commercial landscapes, their vulnerabilities have also come to light. Do we stop planting them? I think the broader question is, should we further diversify our landscapes to minimize infestations and species failures? By the way, let's not plant them where soils are heavy and receive too much water, okay? When designers specify plants and trees, they have a responsibility to recognize these challenges and make informed decisions, in part to give their projects the best opportunities to survive.
West Valley College Campus Location: Arbutus 'Marina'
Cilker (south dry creek bed garden)
Lat: 37°15'54.22"N
Long: 122° 0'39.87"W
Another good overview from landscape architect Jeff Wortham, a Bay Area designer. While Mr. Wortham mentions thinking the species is a hybrid possibly from our native madrone, this appears to be incorrect but understandable why there may be some confusion. Arbutus 'Marina' was an introduction by the famed Saratoga Horticulture Foundation, Inc. (aka Saratoga Horticulture Society right near West Valley College), whose records are now maintained by the University of California, Davis. The introduction was first described by the Saratoga Horticulture Foundation, Inc., with a propagation of cuttings from a specimen found in San Francisco. It is an interesting read, including how the species was named after the Marina District in the City.
facts
Botanical Name: Arbutus 'Marina'
Arbutus: Traditional Latin name for the species, Arbutus unedo.
Common Name: Strawberry tree
Family Name: Ericaceae
Origin: Southern Europe
design considerations
Positioning: Lawn (with good drainage), background
Garden Themes: Mediterranean/dry, coastal, kitchen
Uses: Edible, raised planter, border, accent, informal hedge, screen, focal point, street tree, shade, green stormwater infrastructure
identifying characteristics
Type: Evergreen tree
Form: Round
Texture: Medium
Size: 25' (multi.) to 40' (standard) tall and wide
Outstanding Feature(s): Flower, fruit, bark
Bark: Red-brown, exfoliating, showy
Leaf:
Type: Simple
Arrangement: Alternate
Shape: Oblanceolate, obovate
Margin: Serrate
Color: Medium green
Surface: Smooth, slightly glossy
Flower: Autumn into Winter. Pink, urn-shaped, small, in panicles. Showy.
Fruit: Autumn into Winter (approximately one year after bloom). Attractive, showy, round, highly textured fruit is bright green when young turning yellow, orange, then red when ripe. Flowers and fruit at all stages may be present at the same time. Edible (recipes online).
cultural requirements, tolerances & problems
Sunset Zones: 8, 9, 14-24
USDA Zones: 9-11
Light: Full sun
WUCOLS SF Bay Area Hydro Zone: Low
Soil:
Texture: Sand, loam, rocky (clay if well composted and draining)
Moisture Retention: Well-drained. Accepts brief periods of dryness.
pH: Very acidic to slightly alkaline
Tolerances: Heat, drought, pollution, coastal, lawn planting with proper drainage
Problems: Fruit drop may be messy
Branch Strength: Strong
Insects: Scale, thrips, aphids, leaf miners, psyllids, white flies
Disease: Anthracnose, phytophthora, root rot, rust, sudden oak death, leaf gall, leaf spot
citations & attributions
Norris Brenzel, K. (Ed.). (2012). The New Sunset Western Garden Book. New York: Time Home Entertainment, Inc.
Robertson, B. (July 5, 2019). "What's killing the colorful strawberry tree?" Marin Independent Journal, San Rafael. Accessed on September 21, 2021, from https://www.marinij.com/2019/07/05/uc-marin-master-gardener-strawberry-tree-pest-and-problem/.
SelecTree. UFEI. "Arbutus 'Marina' Tree Record." 1995-2021. Cal Poly State University, San Luis Obispo. Accessed on September 21, 2021, from https://selectree.calpoly.edu/tree-detail/174.
UC IPM. "Madrone." University of California Agriculture and Natural Resources, California Statewide. Accessed on September 21, 2021, from http://ipm.ucanr.edu/PMG/GARDEN/PLANTS/madrone.html.
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.
Photos:
All photos by TELCS.