Dichotomous table for gallers on Linum
by Hans Roskam
1a On shoot parts => 2
1b Roots with nodular swellings. L. usatissimum: Meloidogyne hapla
2a On shoot tips or flowers => 4
2b On leaves or stems mainly of young plants => 3
3a Weak swellings bearing pale yellow spermogonia and orange aecia on cotyledons or young stems. Linum spp.: Melampsora liniperda
= On L. catharticum lives Melampsora lini
3b Young plants largely disfigured, excessively leafy, shoots thickened basally, sometimes ± curved. Leaves clustered, undulate, ± swollen and twisted. Occasionally localised, ± irregular, spongy, pale green swellings also on higher inserted, stunted stem parts and leaves of further developing plants. L. usitatissimum, tenuifolium: Ditylenchus dipsaci
4a On shoot tips or terminal shoots => 5
4b Greened flowers on ± stunted plants. L. catharticum: Unidentified gall mite
= The gall midge Contarinia lini is galling flower buds of L. austriacum
5a Terminal leaves widened, keel-like, making a larval chamber, about 8 x 4 mm long, containing a single larva. Neighbouring leaves ± disfigured and clustered, rosette-like. L. alpinum, austriacum, bienne, catharticum, tenuifolium, usitatissimum: Dasineura sampaina
5b Variously disfigured, pale leaves clustered on shoot tips of distorted plants. L. usitatissimum: Thrips linarius and/or Th. angusticeps