Plant Parasites of Europe

leafminers, galls and fungi

gallers on genus Geum

Dichotomous table for gallers on Geum

by Hans Roskam

1a On leaves or flowers => 3

1b On shoot tips or stems => 2

2a Weak swelling of petiole or shoot axis below a node. G. urbanum: Unidentified weevil

2b Leaves at shoot tip tuft-like clustered; leaf blades ± folded upwards; main venation ± creased and thickened. Containing white larvae. G. aleppicum, rivale, urbanum: Contarinia gei

3a On flowers => 11

3b On leaves => 4

4a Leaf folds or – curls => 8

4b Leaves with abnormal pubescence, warts, pustule-shaped galls or irregular fleshy swellings => 5

5a Warts or pustules => 7

5b Leaves with fleshy galls or with felt-like pubescence => 6

6a Leaf blade, also its midrib, with fleshy swellings about 0.4–12 mm long, sometimes coalescing, irregular, pale- to yellow-green, on both sides of which an intercellular mycelium develops a cottony covering bearing asci. G. montanum: Taphrina potentillae

6b Leaf blade often severely disfigured, with at first whitish, soon brown-red erineum on underside, often along the veins; corresponding, at first pale green, then ± reddened upward archings on upperside, also erinea on both sides of leaf; erinea occasionally extending onto leaf midrib and petiole, shoot axis, flower peduncles and calyx leaves. Hairs cylindrical. G. aleppicum, molle, montanum, rivale, urbanum: Cecidophyes nudus

7a Small warts on leaf blade, midrib and petiole, up to 1 mm across, sometimes coalescing into expanded crusts, ± golden-yellow translucent. Geum spp.: Synchytrium aureum

7b Leaf blade with rotund pale coloured bordered pustules. G. rivale: ? gall midge

8a Leaf-blade curled, caused by aphids or spittlebugs => 10

8b Leaf blades of basal leaves or leaves on stem folded or rolled at margin, caused by gall midges or sawflies => 9

9a Leaflets, starting at midrib, variously folded upwards. Veins thickened; leaf blade ± twisted. Whitish larvae in folds on upper side. G. aleppicum, rivale, urbanum: Contarinia gei

9b Leaf blades, often of several leaflets as well as entire leaves, loosely clustered upwards, or remaining rolled inwards, beginning at margin, without substantial thickening. At first, hyaline-green caterpillars, bearing many forked setae, develop in the sometimes pale green roll and the wall of the roll is soon eaten away. Each roll containing a single, or several larvae. G. urbanum: Blennocampa sp.

10a Various malformations of leaves, caused by aphids. G. rivale, urbanum:
Macrosiphum gei

10b Often associated with strong downward deflection, ± bumpy, often dark-green curling of leaf. Geum spp.: Philaenus spumarius

11a Flowers contain gall midge larvae. Receptacle slightly swollen, calyx and corolla little changed; between the ± strongly reduced central flower parts are several red midge larvae. G. reptans: Geomyia alpina

11b Various greening of flowers. G. rivale, urbanum: ? gall mite

Last modified 18.xi.2023