54. Aronia Medikus, Philos. Bot. 1: 140, 155. 1789.
Chokeberry [Greek Aria, name for whitebeam (formerly a species of Sorbus), alluding to resemblance to chokeberry fruit]
Richard J. Pankhurst†
Adenorachis (de Candolle) Nieuwland; Pyrus Linnaeus sect. Adenorachis de Candolle; Sorbus Linnaeus sect. Aronia (Medikus) C. K. Schneider
Shrubs, 8–20 dm; ˂suckering˃. Stems 1–20+, erect; bark gray or brown, ˂smooth˃; short shoots absent; unarmed; appressed-pilose, glabrous, or glabrescent. Leaves deciduous, cauline, simple; stipules persistent, adnate to petiole, narrowly triangular, margins glandular; petiole present; blade elliptic to obovate, 2.5–7.5(–18) cm, membranous, margins flat, glandular serrulate-dentate, venation pinnate, surfaces glabrous or glabrescent to pilose (or villous). Inflorescences lateral and apparently terminal, 5–12(–20)-flowered, corymbose, appressed pilose; bracts reduced to glands; bracteoles reduced to glands. Pedicels present. Flowers: perianth and androecium epigynous, 12–20 mm diam.; hypanthium campanulate, 1–2 mm, glabrous or villous; sepals 5, erect, triangular; petals 5, white to pale pink, elliptic to orbiculate, ˂base clawed˃; stamens 16–22, equal to petals; carpels 5, connate proximally, adnate to hypanthium, hairy, styles terminal, distinct; ovules 2. Fruits pomes, red or black, obovoid or subglobose, 6–9(–11) mm, glabrous or pilose; hypanthium persistent; sepals persistent, ± appressed; carpels cartilaginous; styles ˂and often filaments˃ persistent. Seeds 1–8 per pome, ˂2–3 mm˃. x = 17.
Species 2 (2 in the flora): e North America.
Aronia has been included in Photinia (K. R. Robertson et al. 1991) on morphologic evidence, but C. Kalkman (2004) doubted this conclusion; a phylogenetic analysis by C. S. Campbell et al. (2007), using chloroplast and nuclear DNA sequence data, did not find a close relationship between A. arbutifolia and P. villosa. Historically, species of Aronia have been assigned variously to Adenorachis, Crataegus, Halmia M. Roemer, Malus, Mespilus, Pyrus, and Sorbus. Aronia latifolia Riddell from Kentucky appears to be a form of Amelanchier canadensis. Aronia is cultivated for food (juice, wine, and jam, and as a soft drink flavoring) and as an ornamental for its leaf color, for example, in the former Soviet Union (as A. mitschurinii A. K. Skvortsov & Maitulina), Sweden (H. A. Persson Hovmalm et al. 2004), and in North America.
Experiments by J. W. Hardin (1973) suggested that species of Aronia are variously outbreeding, self-compatible, or apomictic. They can also hybridize with Sorbus, forming the intergeneric hybrid ×Sorbaronia C. K. Schneider (see 53. Sorbus). The primary pollinators are thought to be small bees.
Varieties have been described for each species, but they are not recognized here as they appear to represent merely extremes of variation.
Aronia ×prunifolia (Marshall) Rehder [Mespilus prunifolia Marshall; Adenorachis atropurpurea (Britton) Nieuwland; Aronia atropurpurea Britton; A. floribunda (Lindley) Sweet; Photinia floribunda (Lindley) K. R. Robertson & J. B. Phipps; Pyrus floribunda Lindley], the purple chokeberry, is intermediate between the two species in indumentum but has purple pomes. It is found in St. Pierre and Miquelon, eastern Canada (New Brunswick, Newfoundland, Nova Scotia, Ontario, Prince Edward Island, and Quebec), and the eastern United States (Connecticut, Delaware, District of Columbia, Florida, Illinois, Indiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, New Hampshire, New Jersey, New York, North Carolina, Ohio, Pennsylvania, Rhode Island, South Carolina, Tennessee, Vermont, Virginia, West Virginia, and Wisconsin).
J. W. Hardin (1973) concluded that the two species are fairly distinct but that Aronia ×prunifolia tends to obscure the boundary between them, making meaningful identification difficult. The fact that the putative hybrid tends to make apparently normal fruit could be the result of apomixis. It could also explain why it has been able to spread beyond the range limits of at least one of its putative parents.
SELECTED REFERENCE Hardin, J. W. 1973. The enigmatic chokeberries. Bull. Torrey Bot. Club 100: 178–184.