Plant Parasites of Europe

leafminers, galls and fungi

Gymnosporangium clavariiforme

Gymnosporangium clavariiforme (Wulfen) de Candolle,1805

on woody Rosaceae

Gymnosporangium clavariiforme: gall on Crataegus monogyna

Crataegus monogyna, België, prov. Namen, Ave-et-Auffe © Jean-Yves Baugnée, det. Arthur Vanderweyen

Gymnosporangium clavariiforme: gall on Crataegus monogyna

underside, with aecia

Gymnosporangium clavariiforme on Crataegus monogyna

Crataegus monogyna: aecia with long peridia, at the underside of the leaf, Nieuwendam

Gymnosporangium cf clavariiforme: gall on Crataegus monogyna

Crataegus monogyna, Balloo © Ben van As (identification tentative)

Gymnosporangium cf clavariiforme: gall on Crataegus monogyna

same leaf, underside


The aecia are sitting on a swollen part of the underside of the leaf, sometimes even on a fruit. Peridium cylindrical, 2-3 mm, fraying out at the tip. The cells of the peridium are densely and coarsely verrucose.

spermogonia, aecia

woody Rosaceae, oligophagous

Amelanchier ovalis; Aroniax prunifolia; Cotoneaster nummullarius; Crataegus azarolus, laevigata, macrocarpa, microphylla, monogyna, nigra, orientalis, pentagya, sanguinea, x sorbifolia; Cydonia oblonga; Malus domestica, sylvestris; Mespilus germanica; Pyrus communis, syriaca; Sorbus aria, arranensis, aucuparia, latifolia, meinichii, neglecta, torminalis.

Crataegus is the most important hostplant by far.

on Juniperus

Gymnosporangium clavariiform: telia on Juniperus communis

Juniperus communis, Mantingerzand, 3.iv.2019 © Ben van As

Gymnosporangium clavariiforme

Juniperus communis: telia; Belgium, prov, Namur, Ave-et-Auffe © Jean-Yves Baugnée, det. A Vanderweyen: aspect after a dry period

Gymnosporangium clavariiforme: teliospores

Juniperus communis, from González-Fragoso (1925a): teliospores


The telia develop on the branches. They are shriveled and brittle when dry, not very conspicuous. Under rainy conditions, however, the swell very strongly and take an orange-red color. They are much higher than wide. The swelling is the result of the intake of water by the pedicels of the spores. The two-celled teliospores are long, 13-20 x 50-86 µm, other sources write 10-22 x 40-120 µm; each cell with 2 germination pores close to the separation wall. Sometimes witches’ brooms are formed.


Cupressaceae, monophagous

Juniperus communis & subsp. nana, drupacea, excelsa, foetidissima, oxycedrus, rigida.


Mycodiplosis gymnosporangii.


Bahcecioglu & Kabaktepe (2012a), Bahçecioğlu, Kabaktepe & Yildiz (2006a), Brandenburger (1985a: 29), Buhr (1964b), Bellmann (2012), Coulianos & Holmåsen (1991a), Dauphin & Aniotsbehere (1997a), Dervis, Dixon, Doğanlar & Rossman (2010a), Gäumann (1959a), González-Fragoso (1925a), Helfer (2005a), Henderson (2000a, 2004a), Jage, Kruse, Kummer ao (2013a), Klenke & Scholler (2015a), Koops (2013a), Kozłowska, Mułenko & Heluta (2015a), Kruse (2019a), Kummer (2012a), Llorens i Villagrasa (1984a), Maier, Begerow, Weiß & Oberwinkler (2003a), Poelt & Zwetko (1997a), Preece & Hick (1994a), Redfern & Shirley (2011a), Roques, Cleary, Matsiakh & Eschem (2017a), Roskam (2009a), Ruszkiewicz-Michalska (2006a), Savchenko, Heluta, Wasser & Nevo (2014c), Savchenko, Wasser, Heluta & Nevo (2019a), Termorshuizen & Swertz (2011a), Tomasi (2012a, 2014a), Tóth (1994a), Unamuno (1941b), Vanderweyen & Fraiture (2008a), Wilson & Henderson (1966a), Zhao, Liu, Li & Cai (2016a), Unamuno (1942a), Woods, Stringer, Evans & Chater (2015a).

Last modified 18.xi.2021