Dichotomous table for gallers on Centranthus
by Hans Roskam
1a Malformation of vegetative parts => 2
1b Flowers double, leaves disfigured. C. calcitrapa, macrosiphon, ruber:
Unidentified gall mite
2a Malformations caused by animals => 3
2b Upper side of the leaf with pale, eventually brown, spots. Underside with a greyish white down of erect conidiophores that are branching several times apically, each branch ending in a ± globular conidium. C. ruber: Peronospora centranthi
3a Axial parts of flowering and vegetative shoots ± stunted at tip; the variously disfigured organs clustered. Flower buds mostly stunted; leaves ± reduced, deflected and curled. Containing black aphids. C. calcitrapa, ruber: Aphis fabae
3b Leaves as well as bracts with pale green or reddened, ± fleshy thickened upward rolls of margin; smaller leaves completely disfigured. Infected flowers swollen, their parts variously disfigured and greened. C. angustifolius, calcitrapae, ruber: Trioza centranthi