Aronia is a genus of deciduous shrubs, the chokeberries, in the family Rosaceae, native
to eastern North America and most commonly found in wet woods and swamps. The genus is
usually considered to contain two or three species, one of which is naturalized in Europe.
A fourth form that has long been cultivated under the name Aronia is now considered to
be an intergeneric hybrid, Sorbaronia mitschurinii. Chokeberries are cultivated as ornamental
plants and as food products. The berries can be eaten raw off the bush, but are more frequently
processed. They can be found in wine, jam, syrup, juice, soft spreads, tea, salsa, chili
starters, extracts, beer, ice cream, gummies and tinctures. The name "chokeberry" comes
from the astringency of the fruits, which create a sensation making one's mouth pucker.
Chokeberries are often mistakenly called chokecherries, which is the common name for Prunus virginiana.
Further adding to the ambiguity, a variety of Prunus virginiana is named melanocarpa.
This is easily confused with Aronia melanocarpa, commonly referred to as "black chokeberry"
or "aronia berry". Aronia berries and chokecherries are both high in polyphenolic pigment compounds,
like anthocyanins, further contributing to confusion. In fact, the two plants are only
distantly related within the Rosaceae family.
Identification and taxonomy The leaves are alternate, simple, and oblanceolate
with crenate margins and pinnate venation; in autumn the leaves turn a bold red color.
Dark trichomes are present on the upper midrib surface. The flowers are small, with 5 petals
and 5 sepals, and produced in corymbs of 10-25 together. Hypanthium is urn-shaped. The fruit
is a small pome, with a very astringent flavor. Aronia has been thought to be closely related
to Photinia, and has been included in that genus in some classifications, but botanist
Cornelis Kalkman observed that a combined genus should be under the older name Aronia.
The combined genus contains about 65 species. In 2004, Kalkman expressed doubt about the
monophyly of the combined group, and new molecular studies confirm this. They do not place these
two genera together or even near one another. In eastern North America, there are two well-known
species, named after their fruit color, red chokeberry and black chokeberry, plus a purple
chokeberry whose origin is a natural hybrid of the two. A fourth species, Aronia mitschurinii,
that apparently originated in cultivation, is also known as Sorbaronia mitschurinii.
Red chokeberry, Aronia arbutifolia, grows to 2–4m tall, rarely up to 6 m. Leaves are
5–8 cm wide and densely pubescent on the underside. The flowers are white or pale pink,
1 cm wide, with glandular sepals. The fruit is red, 4–10 mm wide, persisting into winter.
Black chokeberry, Aronia melanocarpa, tends to be smaller, rarely exceeding 1 m tall,
rarely 3 m, and spreads readily by root sprouts. The leaves are smaller, not more than 6-cm
wide, with terminal glands on leaf teeth and a glabrous underside. The flowers are white,
1.5 cm wide, with glabrous sepals. The fruit is black, 6–9 mm wide, not persisting into
winter. The Purple chokeberry, Aronia prunifolia apparently
originated as a hybrid of the black and red chokeberries but might be more accurately
considered a distinct species than a hybrid. Leaves are moderately pubescent on the underside.
Few to no glands are present on the sepal surface. The fruit is dark purple to black,
7–10 mm in width, not persisting into winter. There are purple chokeberry populations which
seem to be self-sustaining independent of the two parent species – including an introduced
one in northern Germany where neither parent species occurs – leading botanist Alan Weakley
to consider it a full species rather than a hybrid. The range of the purple chokeberry
is roughly that of the black chokeberry; it is found in areas where the red chokeberry
is not. Products and uses
The chokeberries are attractive ornamental plants for gardens. They are naturally understory
and woodland edge plants, and grow well when planted under trees. Chokeberries are resistant
to drought, insects, pollution, and disease. A number of Cultivars, including A. arbutifolia
'Brilliant' and A. melanocarpa 'Autumn magic', have been selected for their striking fall
leaf color. The Voruta label exports a Chokeberry wine
from Lithuania. In Poland they are dried to make a herbal tea which may be blended with
other more flavorful ingredients including blackcurrant. Aronia is also used as a flavoring
or colorant for beverages or yogurts. Juice from the ripe berries is astringent, semi-sweet,
sour, and contains a low level of vitamin C. The berries have their own unique flavor
and in addition to juice they can be baked into soft breads. In the United States and
Canada, aronia berries are used in juice blends for color and marketed for their antioxidant
properties. Polyphenol content
Aronia melanocarpa has attracted scientific interest due to its deep purple, almost black
pigmentation that arises from dense contents of polyphenols, especially anthocyanins. Total
polyphenol content is 1752 mg per 100 g in fresh berries, anthocyanin content is 1480 mg
per 100 g, and proanthocyanidin concentration is 664 mg per 100 g. These values are among
the highest measured in plants to date. The black aronia species contains higher levels
of anthocyanins than purple or red aronia, whereas the order of total polyphenols was
reported as purple = red > black. The plant produces these pigments mainly in
the leaves and skin of the berries to protect the pulp and seeds from constant exposure
to ultraviolet radiation and production of free radicals. By absorbing UV rays in the
blue-purple spectrum, leaf and skin pigments filter intense sunlight, serve antioxidant
functions and thereby have a role assuring regeneration of the species. Brightly colorful
pigmentation also attracts birds and other animals to consume the fruit and disperse
the seeds in their droppings. Analysis of polyphenols in chokeberries has
identified the following individual chemicals: cyanidin-3-galactoside, cyanidin-3-arabinoside,
quercetin-3-glycoside, epicatechin, caffeic acid, delphinidin, petunidin, pelargonidin,
peonidin, and malvidin. All these except caffeic acid are members of the flavonoid category
of phenolics. For reference to phenolics, flavonoids, anthocyanins,
and similar plant-derived phytochemicals, Wikipedia has a list of phytochemicals and
foods in which they are prominent. ORAC Score
In a standard measurement of antioxidant strength, the oxygen radical absorbance capacity or
ORAC, demonstrates aronia to have one of the highest values yet recorded for a fruit — 16,062
micromoles of Trolox Eq. per 100 g. The components contributing to this high measurement were
both anthocyanins and proanthocyanidins, with the proanthocyanidin level "among the highest
in foods, which may explain their potent astringent taste."
No relevant correlation between ORAC score and human health has been demonstrated, and
some scientists consider it biologically irrelevant to human nutrition.
Preliminary research Basic research on aronia has addressed potential
mechanisms for reducing risk of disease. Models under evaluation include:
reduction of blood cholesterol colorectal cancer
cardiovascular disease chronic inflammation
gastric mucosal disorders eye inflammation
liver failure anti-adhesion properties
breast cancer arterial hypertension
cervical cancer immunomodulation
References
Further reading Aronia: The North American super berry with
cancer-fighting properties by Chris Kilham Fox News, June 7, 2013
External links Evergreen Native Plant Database
Hortnet: Aronia melanocarpa, Plant of the Month
Plants for a Future page about Aronia arbutifolia