Dichotomous table for gallers on Helichrysum
(see also Gnaphalium)
by Hans Roskam
1a On root collar, inner basal rosettes or on above-ground plant parts => 2
1b Spindle- or nodule-shaped swellings on roots, up to 5 mm long. Helichrysum spp.: Meloidogyne hapla
2a On upper stem parts, leaves or inflorescences => 4
2b Inside basal rosettes or on root collar => 3
3a Top of rosettes including an almost onion-shaped gall, up to 8 mm high and 5 mm wide. One larva inside. H. arenarium: Actinoptera discoidea
3b Globular or nodular, up to 1 mm long galls which are sometimes clustered and variously coalesced on root collar. The inside filled with initially bright-, later on chestnut brown spore masses. H. arenarium: Entyloma magnusii
4a On leaves and inflorescences => 6
4b On shoots => 5
5a Spindle-shaped swellings of the stems or inflorescence, up to 25 mm long. Later on the caterpillar bores downward in the pith over various length. H. arenarium: Unidentified lepidopteran
5b Spindle-shaped stem swellings about 6 mm long and 4 mm thick. Containing a single larva. H. arenarium: Actinoptera discoidea
5c Terminal leaves grouped in a subspherical mass of 10–15 mm in diameter, or terrminal bud swollen, ovoid or spindle-shaped (10 x 4.5 mm), covered with pubescent leaves. Large axial cavity containing a single larva. H. italicum, litoreum, pendulum, stoechas: Actinoptera mamulae
6a On inflorescences or capitula => 7
6b The middle part of single or several leaves variously bent downward and ± curled by froth-covered nymphs. H. bracteatum: Philaenus spumarius
7a Inflorescence stunted, bunched. Leaves ± rolled. Helichrysum spp.: Brachycaudus helichrysi
7b Capitula deformed; receptacle hardened. Containing a single larva. H. arenarium: Actinoptera discoidea