gallers on Arenaria

1a On flowers or fruits => 6

1b On vegetative organs => 2

2a Malformations expanded over ± substantial areas of the shoot => 3

2b On smaller leaves, petioles or sometimes locally bent stems, spots pad-like arched on underside, bearing ± elongated bulges with terminally papilla-like narrowed telia with 2-celled teliospores which fall apart easily and then seemingly 1-celled. Sori on underside of larger leaf blades usually in circular arrangement in discoloured not thickened spots. Sori soon becoming powdery white because of direct germination of the teliospores. A. montana, retusa, serpyllifolia, tenuifolia: Puccinia arenariae

2c Sori usually more expanded. Fungus distinguished by black, terminally rounded, 2-celled telia. A. serpyllifolia: Puccinia hysteriiformis

3a Diseased parts etiolated, with sori of fruiting bodies of fungi => 5

3b Galls caused by animals => 4

4a Stem ± stunted, spongy, swollen; galls at surface ± rugose, pale green. A. serpyllifolia: Ditylenchus dipsaci

4b Leaves rolled downwards at tip of weakly stunted shoots. A. serpyllifolia: Myzus certus

5a Plants usually completely diseased. Shoots developing earlier and rigidly erect leaves pale green, narrowed, with yellow sori on underside. A. serpyllifolia: Melampsorella caryophyllacearum

5b Early infected buds or shoots develop further rigidly erect. Leaves pale green, small, partially spoon-like, arched downwards, with a down of branched conidiophores on underside. A. ciliata, foliosa, serpyllifolia: Peronospora campestris

6a Malformations of fruits => 7

6b Flower buds outwardly hardly changed. Anthers temporarily swollen, soon filled with black-violet spore masses, with dusting later on. A. ciliata: Microbotryum violaceum

6c Flowers ± swollen globularly, unopened. Inner organs soon destroyed and replaced by spore balls consisting of a yellowish-brown powdery dust. A. tenuifolia: Thecaphora saponariae

7a Capsule enlarged on thickened fruit peduncle, oval; contains a beetle larva. A. serpyllifolia: Unidentified snout beetle

7b Capsule outwardly hardly changed. Seed rudiments, also placenta, temporarily swollen, soon filled with red-brown spore masses. A. ciliata, graminea, obtusiflora incl. subsp. ciliaris, serpyllifolia: Microbotryum duriaeanum