Image of Uromyces pisi-sativi (Pers.) Liro 1908

Description:

Syn.: Uromyces pisi, Puccinia pisi - Slo.: grahova rja - Habitat: Relatively dry sandy grassland, grazed by sheep, shallow soil, almost flat terrain, full sun, exposed to direct rain, average precipitations ~ 3.000 mm/year, average temperature 8-10 deg C, elevation 540 m (1.800 feet), alpine phytogeographical region. - Substratum: Euphorbia cyparissias plant. - Comments: This rust fungus modifies its host plant Euphorbia cyparissias. Infected plants usually don't produce fertile flowers and are much more slender and taller than normal. But they form a kind of pseudo-flowers, a rosette of leaves at the top of stalks, resembling true flowers. Fungus produces nectar similar to nectar of healthy plants. It attracts ants and other insects, both on healthy and infected plants. For over 100 years this host-pathogen pair has been subject to much speculation concerning the function of nectar-producing spermatia. Today, it is generally assumed that they are produced to attract insects for fungal fertilization (more in Ref.: 4.). - Urediniospores produced by orange vegetation producing pustules uredia. - Urediniospores finely warty, dimensions: 24.0 (SD = 1.2) x 21.5 (SD = 0.7) micr., Q = 1.12 (SD = 0.07), n = 25. - Ref.: (1) http://www.agroatlas.ru/en/content/diseases/Fabacee/Fabacee_Uromyces_pisi/ (2) http://www.ncbi.nlm.nih.gov/pubmed/10636829 (3) http://www.uni-graz.at/walter.obermayer/plants-of-styria/images/euphorbia-cyparissias.html (4) http://www.amjbot.org/cgi/content/full/87/1/48#F1 (5) http://e-collection.library.ethz.ch/eserv/eth:23187/eth-23187-01.pdf