Taphrina alni

"Alder tongue gall"
Scientific classification
Kingdom: Fungi
Phylum: Ascomycota
Class: Taphrinomycetes
Subclass: Taphrinomycetidae
Order: Taphrinales
Family: Taphrinaceae
Genus: Taphrina
Species: T. alni
Binomial name
Taphrina alni
(Berk. & Broome) Gjaerum, 1966
Synonyms

Taphrina amentorum
Exoascus amentorum
Exoascus alni-incanae J.G.Kuhn
Ascomyces alni Berk. & Broome
Ascomyces alnitorquus (Tul.) anon. ined.
Exoascus alnitorquus (Tul.) Sadeb. 1884
Taphrina alni-incanae (J.G. Kühn) Magnus 1890
Taphrina alnitorqua Tul. 1866

Taphrina alni is a fungal plant pathogen that causes Alder tongue gall, a chemically induced distortion of female alder catkins (Alnus glutinosa).[1][2]

T. alni produces a distinctive tongue-like growth which derives mainly from the ovarian tissues of the alder catkin or from the bracteoles. These alder pseudocones may carry several tongue galls, each of which usually appear to come from the same position; those curling down usually come from the bracteoles tissues and those projecting upwards usually come from ovarian tissues.[3]

Alder pseudocone and tongue gall in winter.
Unusually large languets

Distribution

This gall was rare in the United Kingdom and is absent from many of the published gall keys, although common in Western Europe. It was recorded in Cornwall first in the 1940s,[4] and then in Northumberland, Ayrshire and Skye, mainly since the 1990s. It is becoming quite common throughout the United Kingdom.[4][5][6]

Life cycle

The gall develops on the maturing pseudocones and the spores produced are carried by the wind to other trees.

Infestations of Alder tongue galls

Removing and destroying the galls may help to reduce the infestation. While fairly large, and sometimes present in quite large numbers specimens, they cause no measurable harm.

Structure and appearance

A developing languet
Pseudocone with developing languet
A mature languet
Pseudocone with mature languet
Languets on Alder pseudocones

The gall, known as a 'languet',[7] develops and emerges from between the outer scales like a flat, elongated flag with a hard, smooth and slightly shiny surface lacking any hairs. The outer edges are rounded and the tip is broader than the foot of the 'flag'. Early in the season the flag is fresh and green, but the colours soon start to vary from pale green to yellow, pink, red, purple and orange. Later the galls turn brown or black and remain on the tree for a long time (until the next season).[8] The gall is therefore very persistent and remains attached to the pseudocone throughout its existence, even remaining attached after storms have detached branches and pseudocones.

See also

References

Notes
  1. ↑ Ellis, Hewett A. (2001). Cecidology. Vol.16, No.1. p. 24.
  2. ↑ Clarification of synonyms
  3. ↑ Ellis, Hewett A. (2001). Cecidology. Vol.16, No.1. p. 28.
  4. 1 2 Redfern, Page 223
  5. ↑ Tongue gall on alder
  6. ↑ Ellis, Hewett A. (2001). Cecidology. Vol.16, No.1. p. 30.
  7. ↑ Ellis, Hewett A. (2001). Cecidology. Vol.16, No.1. p. 27.
  8. ↑ Gall Fungi
Sources
  1. Redfern, Margaret & Shirley, Peter (2002). British Plant Galls. Identification of galls on plants & fungi. AIDGAP. Shrewsbury : Field Studies Council. ISBN 1-85153-214-5.
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