gallers on Arrhenatherum

1a On parts above ground => 2

1b Roots with spindle-shaped, half-screw-shaped bent swellings a few mm long; tissue with cavities. A. elatius: Subanguina radicicola

1c Similar, but compact, malformations sometimes on sagging root tips. A. elatius: Meloidogyne hapla

1d Roots of A. elatius may also become infected with Heterodera avenae

2a Malformations only on inflorescences or flowers => 6

2b On vegetative parts => 3

3a Leaves with long, parallel stripes caused by rusts or smuts => 5

3b Malformations of shoots caused by animal parasites => 4

3c Stems within the leaf sheaths, sometimes also the outside of the sheaths, covered by a dark brown layer of spores. A. elatius: Tranzscheliella hypodytes

4a Shoot conspicuously shortened, swollen at base. Stem only weakly developed, often not protruding from the sheath. Inflorescence with strongly etiolated spikes, sometimes also ± bleached. Contains many eelworms. A. elatius: Ditylenchus dipsaci

4b Shoot axis stunted; panicle stunted, bleached; contains a fly maggot. A. elatius: Unidentified Chloropidae

4c Longitudinally arranged, about 10 (12) mm long saddle-shaped, terminally rimmed depressions, which occur with several under the slightly swollen leaf sheaths above the nodes. Contain blood red midge larvae. A. elatius: Haplodiplosis marginata

4d Lateral swelling of stem, just above the ground, 10–12 mm long and 5–6 mm broad; large chamber contains a single larva. A. elatius: Tetramesa sp.

4e Black aphids under crumpled leaves. A. elatius: Melanaphis pyraria

4f Leaf sheaths of the upper part of stem ± bladder-like swollen; inside are many yellow- to brownish-green aphids, up to about 2 mm long. A. elatius: Laingia psammae

5a Spores solitary, or with 2–3 in balls, enveloped by sterile cells. A. elatius: Urocystis avenae-elatioris

5b Spores solitary, rotund- oblong-oval, densely warty. A. elatius: Ustilago notarisii

5c Long conspicuous stripes on chlorotic leaf tissue caused by rust fungus. A. elatius: Puccinia striiformis

6a Inflorescences disfigured by smut fungi => 7

6b Panicle stunted, axial parts wriggled, spikes disfigured, clustered. A. elatius: Unidentified eelworm

6c Inflorescence contains yellow midge larvae. A. elatius: Contarinia arrhenatheri

7a Ovaries and flower peduncle, sometimes also the spikelets, swollen, and soon filled with masses of agglutinated spores. Often all panicles and flowers of a plant with smut, exceptionally only with some apical flowers remaining normal. Unfolding panicles not spreading; spores dispersing at once. A. elatius: Ustilago hordei

7b Malformations similar in all parts; spore masses hardened however, spores not dispersing immediately. A. elatius: Ustilago avenae