Plant Parasites of Europe

leafminers, galls and fungi

gallers on Alcea

Dichotomous table for gallers on Alcea

(incl. Althaea)

by Hans Roskam

1a On parts above ground => 3

1b On roots => 2

2a Side roots with mainly rounded, nodular swellings. Althaea officinalis; Alcea rosea & var. nigra: Meloidogyne hapla

2b Main root thickened, beet-like. Central chamber contains a single larva. Althaea hirsuta: Unidentified coleopteran

3a Malformations caused by animal parasites => 4

3b Leaves and all other green organs, as well as stem, epicalyx and even young ovaries, with rotund, 1‒2 mm broad, cushion-shaped swellings, soon bearing at first yellow-red, later on brown telia. Telia germinating immediately, giving them a whitish-powdery appearance. Alcea spp.; Althaea spp.: Puccinia malvacearum

4a Malformations lacking conspicuous additional pubescence => 5

4b Leaves on Althaea officinalis with localised erinea. Unidentified gall mit

5a Malformation of leaf blades => 6

5b A single mericarp contains a beetle; there also pupation takes place. Infected flowers fade prematurely. Alcea dissecta, rosea, setosa: Rhopalapion longirostre

6a Leaf blades, usually of many terminal leaves, on ± stunted shoots loosely arched downwards and ± curled. Alcea biennis, nudiflora, rosea; Althaea officinalis: Aphis althaeae

6b Leaf blade ± strongly wrinkled, margins deflected. Sometimes the flower buds are also disfigured. Contain pale green aphids with siphunculi half as long or equalling cauda. Alcea rosea, Althaea officinalis, cannabina: Acyrthosiphon malvae

6c Venation close to infestation stunted and deflected; neighbouring leaf blade part curled, deep green, rolled- or curved downwards, nest-like. Contains a froth-covered nymph. Alcea spp.; Althaea spp.: Philaenus spumarius

Last modified 18.v.2020