Dichotomous table for gallers on Nigella arvensis
by Hans Roskam
1a Stem bulging, swollen, also bent, with oval, rimmed, shallow depressions, which contain inducer. Planchonia arabidis
1b Yellowish, often conspicuous bulges on ± curved stems, petioles, leaves and cotyledons bearing aecia and spermogonia. Puccinia actaeae-elymi
1c In similar aecia in Nigella species develops the usually weakly cecidogenic. Puccinia actaeae-agropyri