Rusts
Rusts are parasites of higher plants. They occur primarily on leaves, needles and cones of broad-leaved and coniferous trees, plants and ferns, without, however, killing the host plant. The rust-coloured spores are spread by the wind.
Rusts often require two host plants. The spores of Puccinia graminis, for instance, germinate in spring on Berberis leaves and penetrate the leaf. After a few days, cup-shaped, ‘ male’ reproductive organs or spermagonia with pycnospores (spermatia) appear on the upper surface of the leaf, and on the lower surface ‘ female’ reproductive organs or aecia with receptacular hyphae. The cups exude a sugary liquid containing pycnospores, which attracts insects.
The insects transport the spores to the receptacular hyphae. The aecidiospores, which are produced after fertilisation, are spread by the wind and infect the grain.
On the grain, uredinia develop, in which the summer spores or urediospores are formed. They can infect new host plants. In autumn, thick-walled winter spores are formed in so-called telia on the grain. The winter spores overwinter in the soil and in spring they form a basidium with basidiospores.
Listed taxa:
Family Pucciniaceae
- Gymnosporangium clavariiforme