Aria mergenthaleriana, or Mergenthaler's whitebeam,Blaich, G. (n.d.). Sorbus mergenthaleriana N.MEY. Retrieved September 4, 2026, from https://guenther-blaich.de/pflseite.php?par=Sorbus+mergenthaleriana&abs=pflfmros&lan=x&grp=a is an apomictic speciesSorbus mergenthaleriana N. Mey. Mergenthaler-Mehlbeere. (n.d.). Botanischer Informationsknoten Bayern. Retrieved September 4, 2026, from https://daten.bayernflora.de/de/info_pflanzen.php?taxnr=26241 of tree in the family Rosaceae endemic to Bavaria, Germany.Aria mergenthaleriana (N.Mey.) Mosyakin, Fedor. & McNeill. (n.d.). Plants of the World Online. Retrieved September 4, 2026, from https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:77371501-1 It is extremely rare and threatened with extinction.
Description
Vegetative characteristics Aria mergenthaleriana is an up to 4–5 m tall shrubMeyer, T. (n.d.). Mergenthalers Mehlbeere (Sorbus mergenthaleri N. Meyer). Blumen in Schwaben. Retrieved September 4, 2026, from https://www.blumeninschwaben.de/Zweikeimblaettrige/Rosengewaechse/regensburg.htm#Mergenthalers%20Mehlbeere or tree. The ovate leaves of the short twigs are 6–7 cm long and those of the long twigs are 7–9 cm long. The leaves have 10–11 pairs of lateral veins. The abaxial leaf surface is pubescent with grey hairs. The petiole is 1.5–2.3 cm long. The autumn leaves have a pure yellow colouration.
Generative characteristics The flowers have two basally fused styles. The anthers are cream-coloured. The ovoid, bright or dark orange accessory fruits with 0.5 mm big lenticels are up to 17 mm long.
Cytology The chromosome count is 2n = 3x = 51. It is triploid.Senckenberg Gesellschaft für Naturforschung. (n.d.). Sorbus mergenthaleriana N. Mey. Chromosomenzahlen Zur Flora Von Deutschland. Retrieved September 4, 2026, from https://chromosomes.senckenberg.de/item/19127
Taxonomy It was first described as Sorbus mergenthaleriana by Norbert Meyer in 2005.Sorbus mergenthaleriana N.Mey. (n.d.). International Plant Names Index. Retrieved September 4, 2026, from https://www.ipni.org/n/77070664-1 It was moved to the genus Aria as Aria mergenthaleriana by Sergei Leonidovich Mosyakin, Mykola Mykhaylovych Fedoronchuk, and John McNeill in 2025.Mosyakin, S. L., Fedoronchuk, M. M., & McNEILL, J. (2025). Simplifying the nomenclature of Sorbus sensu lato: new nomenclatural solutions in Aria and Hedlundia (Rosaceae). Ukrainian Botanical Journal, 82(3), 206-224.Aria mergenthaleriana (N.Mey.) Mosyakin, Fedor. & McNeill. (n.d.-b). International Plant Names Index. Retrieved September 4, 2026, from https://www.ipni.org/n/77371501-1 The type specimen was collected on the 1st of July 2001 by N. Meyer and O. Angerer near Etterzhausen. Etymology The specific epithet mergenthaleriana honours the Bavarian botanist Otto Mergenthaler.
Distribution and habitat
Aria mergenthaleriana is endemic a small area of only about 6.6 km2 near Regensburg, Germany, where it occurs in disused pastures now afforested with pine trees, on the edges of deciduous forest, and on rocks at elevations of 350–400 m above sea level.
Conservation It is cultivated in ex situ conservation collections in several botanic gardens, including the Zoological and Botanical Garden of the City Plzeň,Zoological and Botanical Garden of the City Plzeň. (2020). Index Seminum 2020. Plzeň. the Botanischer Garten der Universität Regensburg,Poschlod, P., & Debus, V. (2025). Regensburgs Grünes Juwel: Ein Führer durch den Botanischen Garten der Universität - Wissenswertes zu Pflanzen, ihrer Geschichte und Heilwirkung. Regensburg; Universitätsbibliothek Regensburg. Botanische Gärten und andere Halter. (n.d.). Verband Botanischer Gärten. Retrieved September 4, 2026, from https://www.verband-botanischer-gaerten.de/Arbeitsgruppen/Botanischer_Artenschutz/Botanische_Gaerten_und_andere_Halter.html and the Rogów Arboretum of Warsaw University of Life Sciences.Szczegółowy wykaz taksonów drzew i krzewów uprawianych w Arboretum. (2025, December 9). Rogów Arboretum of Warsaw University of Life Sciences. Retrieved September 4, 2026, from https://arboretum.sggw.edu.pl/wykaz-a/
References