Ceratonia siliqua

Updated: Sep 25


Where do you fall in the carob or chocolate debate? A general online search illustrates how people take sides for their health benefits or pitfalls and flavor. As a kid, I used to enjoy sugar-laden frozen yogurt smothered in carob chips thinking they were healthy choices. Those days have past, but for this debate, carob trees win hands down for landscape value in California.


Carob as we know it derives from a simple process of roasting and grinding the seed pods from this evergreen tree, Ceratonia siliqua. For ornamental landscapes, carob trees offer opportunities to create dense shade from well-formed trees. To the untrained eye, and maybe from a distance, a carob tree can look a little like our own coast live oaks, or Quercus agrifolia. While the leaflets look a little like leaves from a coast live oak, they are not simple but compound, hence the reference to leaflets. The tree's overall form appears similar as well, however, that is where the similarities end. C. siliqua has an unusual trunk and bark. Older trees will have highly textured surfaces appearing as though old vines had at one time clung and climbed but since fused with its host, folding and undulating; for some specimens seemingly twisting and ascending upwards. High value for its sculptural appeal.


Of course, there are no oak acorns. Instead, C. siliqua produces pods, as can be expected by species within the Fabaceae family of legumes, that reach up to one foot long. For an ornamental landscape, the pods can be a deterrent, giving the tree a messy appearance that is only exasperated when they clutter the ground. That's where maintenance clean-up comes in, or if someone is industrious, take advantage of this opportunity to make the chocolate substitute...unless you are a chocoholic, there is no substitute.


West Valley College Campus Location: Ceratonia siliqua

Music Building (southwest corner)

Lat: 37°15'54.65"N

Long: 122° 0'29.95"W


facts

Botanical Name: Ceratonia siliqua

Ceratonia: Greek, keratonia, a derivative of keras, for horn, as in the shape of the pods

Siliqua: Possibly Greek, silique, or a Roman derivative of siliquastrum, for a plant exhibiting pods

Common Name: Carob tree; St. John's Bread

Family Name: Fabaceae (Caesalpiniaceae)


Origin: Mediterranean


design considerations


Positioning: Background, silhouette

Garden Themes: Mediterranean/dry, coastal, kitchen (perimeter location),

Uses: Edible, large screen, windbreak (may not be suitable for coastal winds)


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: Even pinnately compound

  • Arrangement: Alternate

  • Shape: Leaflets: Obovate

  • Margin: Entire

  • Color: Dull dark to medium green above, light green below

  • Surface: Glabrous, waxy, leathery

Flower: Spring. Green-red small flowers spiral along axis of a raceme, giving an appearance as a catkin.

Fruit: Summer to Autumn. Long red-brown legume, possibly reaching 12" in length, flat. Leathery, mahogany appearance when ripe (seeds rattle inside)


cultural requirements, tolerances & problems


Sunset Zones: 9, 13-16, 18-24; H1

USDA Zones: 8-11


Light: Full sun

WUCOLS SF Bay Area Hydro Zone: Low

Soil:

  • Texture: Sand, loam, clay if well composted and draining

  • Moisture Retention: Well-drained. Accepts brief periods of dryness.

  • pH: Slightly acidic to highly alkaline

Tolerances: Drought, deer

Problems: Fruit drop may be messy if not used for harvest

  • Branch Strength: Medium

  • Insects: Scale

  • Disease: Root crown rot, armillaria

citations & attributions


Bayton, R. (2019). The Royal Horticultural Society's the Gardener's Botanical: An Encyclopedia of Latin Plant Names. London: Mitchell Beazley.


Breen, P. "Ceratonia siliqua." Oregon State University, College of Agricultural Sciences, Department of Horticulture, Corvalis. Accessed on September 24, 2021, from https://landscapeplants.oregonstate.edu/plants/ceratonia-siliqua.


Norris Brenzel, K. (Ed.). (2012). The New Sunset Western Garden Book. New York: Time Home Entertainment, Inc.


SelecTree. UFEI. "Ceratonia siliqua Tree Record." 1995-2021. Cal Poly State University, San Luis Obispo. Accessed on September 23, 2021, from https://selectree.calpoly.edu/tree-detail/306.


UC IPM. "Carob." University of California Agriculture and Natural Resources, California Statewide. Accessed on September 23, 2021, from http://ipm.ucanr.edu/PMG/GARDEN/PLANTS/carob.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.

https://ucanr.edu/sites/WUCOLS/Download_WUCOLS_IV_List/.


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