December 2016 Plant Profile: Arbutus unedo

A. unedo flowers and fruit
A. unedo flowers and fruit

Except for their bright red fruits and similar common names, the Strawberry Tree (Arbutus unedo) and the strawberry (Fragaria spp.) have nothing in common.  This tree is valued as an ornamental broadleaf evergreen for gardens and it has a long history of appreciation in Western cultures.

The species name ‘unedo’ is attributed to Pliny the Elder who said of the fruit “Unum Tantum Edo” (Latin) meaning “I eat only one”.   This has been interpreted as either “it’s not that great” or “it’s so great you only need one.” In honor of Pliny’s description, Carl Linnaeus bestowed the botanical classification as Arbutus unedo in his first volume of “Species Plantarum” (1753).

The Strawberry Tree shows up in various historical accounts of Western culture. The ancient Greeks prized the wood for flute-making. In ancient Roman culture it is mentioned by Pliny the Elder and Ovid. In Italy the poet Giovanni Pascoli describes the tree as a symbol for the Italian flag because they both bear the colors of green, red and white. Its fruit was central to Hieronymus Bosch’s painting ‘Garden of Earthly Delights’. Madrid Spain’s coat of arms features the Arbutus and a bear (‘The Bear and the Strawberry Tree’ or ‘El Oso e El Madrono’).  In Ireland there is an ancient folk ballad “My Love’s an Arbutus.”   Evidence of tree pollen preserved in bogs suggests that the tree was introduced to Ireland in the form of seeds some 4000 years ago during widespread immigration of the Beaker culture in Europe.

Though related to our native madrone (Arbutus menziesii), Arbutus unedo is much more suitable for cultivation in gardens. Strawberry Tree is an almost fault-free evergreen ornamental with year-round interest.   Its leaves are shiny dark green, ovate to 4” long with a serrate edge and red petiole and its multiple trunks have a cinnamon brown bark which exfoliates as it ages. The real show stoppers on this plant are the flowers and fruit, which are both abundant and, unusually, both present on the tree at this time of year.

The flowers are in clusters of tiny white bells (similar to its related genera Arctostyphylos, Pieris and Enkianthus) and are present October to December while the 1” round fruits of the previous year’s pollination are ripening on the tree.  The fruits take 10-12 months to ripen; from green in the spring they begin to turn yellow then orange through summer then ripen to a bright red from October to December at which time they are edible.

elosoeelmadrono
Madrid’s coat of arms “El Oso E El Madroño”

These trees prefer sandy to loamy soils, but can tolerate heavy clay, they take some shade and grow in dappled light as an understory plant where native, and will tolerate maritime climates and pollution. Here in the Pacific Northwest they prefer full sun and grow leggy in too much shade. Like other Mediterranean plants their tolerance for lack of summer rain makes them a great plant for the Pacific NW.

The species trees are wonderful, but there are also various cultivars that offer options.  A. unedo f. rubra, which has earned The Royal Horticultural Society’s Award of Garden Merit, has a red tinge to its flowers and A. unedo ‘Compacta’ is a smaller tree, though still growing over 8’ high and wide, which can be used if space is limited. In general, A. unedo tolerates pruning when branches are young to help keep in bounds, and can make an attractive informal hedge.

 There is some misinformation online about the fruit being poisonous, but it is not and can be eaten fresh or prepared. Folks seem to either like it for its light pear-like flavor or dislike it for its lack of strong flavor and “mealy” texture.   The fruit is ripe when it falls from the tree or, if still on the tree, must be bright red and a bit squishy – people should be aware that the fruits will start to ferment readily once ripe and it is possible to become inebriated from eating too many.

It is used in Southern and Eastern Europe to make alcohol; the Portuguese “Aguardente de Medroñho” and Albanian “Raki Kocimareje” are a couple of examples. There are several Arbutus fruit recipes on line for jams, pies, muffins and candy. Apparently the fruits’ high pectin and natural sugar content make it as ideal for cooking as other fruits which are used more commonly.  Various cultures have also used the fruit, leaves and bark of the plant in traditional folk medicines as an antiseptic, astringent, and tonic due to its antifungal and antibacterial properties. (Please note: this is not a recommendation to “try it at home”.)

Common Names: Strawberry Tree, Cain Apple and Bearberry (English), Madroñhiero (Portugese), Madroños, (Spanish), Corbezzolo (Italian), Koumaria (Greek), Caithne (Gaelic for Cain Apple)
Genus: Arbutus
Species: unedo
Family: Ericaceae
Locations: A. unedo ‘Rubra’ (3) just off Arboretum Dr. S. of Fiddleheads Forest School classroom (652-60*C-E, 20-3E & 21-3E), A. unedo (6) between Graham Visitors Center parking lot and South Patio, A. unedo at the head of Rhododendron Glen (1018-37*A-F, 11-8E & 12-8E). The variety ‘Compacta’ is planted south of the entry drive at the Center for Urban Horticulture.
Origin: Ireland, Southern to Eastern Europe, Turkey, Syria and some parts of North Africa.
Height and Spread: can reach 30’ tall by 25’ wide, but is typically about 15-20’ tall with a 10-15’ spread to the crown.
Bloom Time: early autumn through late winter

Resources:
http://www.pfaf.org/user/plant.aspx?latinname=Arbutus+unedo
http://www.eattheweeds.com/the-strawberry-tree-curse-2/
https://en.wikipedia.org/wiki/Arbutus_unedo
http://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?taxonid=279932&isprofile=0&
http://link.springer.com/article/10.1007/s10068-011-0172-9

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