Puccinia poarum

Puccinia poarum
Scientific classification
Kingdom: Fungi
Division: Basidiomycota
Class: Urediniomycetes
Order: Uredinales
Family: Pucciniastraceae
Genus: Puccinia
Species: P. poarum
Binomial name
Puccinia poarum
E. Nielsen, 1877
Synonyms

Puccinia conspicua Mains 1933
Puccinia liatridis Bethel 1934
Pleomeris poarum (E. Nielsen)
Aecidium tussilaginis
Aecidium compositarum var. tussilaginis (Pers.)

Puccinia poarum,, the coltsfoot rust gall[1] or meadow grass rust, is a plant pathogen. This fungal parasite forms a bright yellow gall, 1–2 cm across, on the underside of leaves of the coltsfoot (Tussilago farfara)[2] and infects, but does not gall grasses of the Poaceae family.[3]

Characteristics

This yellow gall consists of relatively large and circular raised yellow or orange-red spots on the underside of the leaf,[4][5] often with a purple margin[2] and sometimes a central hole. The cup structures on the lower surface are relatively few in number (20-30).[1] The upper surface of the leaf shows a yellow ring and no swelling. The rust has distinctive reproductive structures (aecia and spermogonia), present.[4] The rust is necrophytic, a term applied to a parasitic organism that obtains its nutrients from the dead cells and tissues of its host organism.

Identification

The upper surface of a coltsfoot leaf galled by P. poarum.

Coleosporium tussilaginis is a rust fungus with which P. poarum is sometimes confused. C. tussilaginis usually appears somewhat later in the season and tends, not being a gall, to be spread all over the leaf rather than forming the discrete circular clusters typical of P. poarum; it is also less obvious on the upper leaf surface[6] and lacks the purple margin[2] with the central hole characteristic of the gall.

P. poarum is found on at least seventy plant hosts.[7]

Life-cycle

Life-cycle of a related species Puccinia striiformis var. striiformis
Detail of the P. poarum gall's upper surface on a Coltsfoot leaf.

Peter Nielsen was the first to describe the heteroecious life-cycle of this fungus; it's aecial or sexual phase host is the Coltsfoot, a member of the Asteraceae, spread by airborne spores; its telial or asexual host phase are members of the grass family, the Poaceae.

Heteroecious organisms are those that require two distinct and distantly related hosts (alternate hosts).

Distribution

In the United Kingdom it is locally common[4] and widely distributed.[8] Northern hemisphere to South America.[9]

See also

References

Notes
  1. 1 2 Puccinia poarum. Accessed : 2010-08-17
  2. 1 2 3 Stubbs, Page 70
  3. ↑ Bioimages. Accessed : 2010-08-17
  4. 1 2 3 Redfern, Page 260
  5. ↑ Hancy, Page 106
  6. ↑ Wild About Britain. Accessed : 2010-08-17.
  7. ↑ Fungal database : Accessed 2010-08-17
  8. ↑ NBN Database. Accessed : 2010-08-17
  9. ↑ Fungal Database. Accessed : 2010-08-17
Sources
  1. Hancy, Rex (2000) The Study of Palnt Galls. The Norfolk and Norwich Naturalists' Society.
  2. Redfern, Margaret & Shirley, Peter (2002). British Plant Galls. Identification of galls on plants & fungi. AIDGAP. Shrewsbury : Field Studies Council. ISBN 1-85153-214-5.
  3. Stubbs, F. B. Edit. (1986) Provisional Keys to British Plant Galls. Pub. Brit Plant Gall Soc. ISBN 0-9511582-0-1
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