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 This is
a large timber tree from the mountains of northern Mexico that does not drop
its leaves in autumn. It was
introduced in Riverside, California by Dr. Archie Shamel around 1925 and has
since been spread all over California either from commercial nursery sales or
as an invasive species by seeds. It
has been favored in California for its hansom appearance and drought
tolerance.
The
shamel ash has separate male and female trees. The male pollen grains are 26-28 micrometers and a prime
contributor to wind blown allergens during the winter months. Although the tree has desirable qualities
such as shade production, little attention is given to the adverse effects
its pollen being a prime contributor to respiratory allergies and
asthma. The species is also highly
invasive in home gardens via its airborne seeds. Female trees deposit great quantities of debris that enters
urban sewers and clogs smaller drains.
There
is little hope for a biological control of shamel ash, but restrictive
planting could be implemented. It is
almost impossible to get rid of sprouted seed borne trees as the roots are
deep enough to resproute foliage after cutting.
REFERENCES:
Barderas, R., A.
Purohit, I. Papanikolau, R. Rodríguez, G. Pauli & M. Villalba. 2005. Cloning, expression, and clinical significance
of the major allergen from ash pollen, Fra e 1. Journal of Allergy and Clinical Immunology, 115:
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Bartra, J., J.
Mullol, A. del Cuvillo,, L. Dávila,, M. Ferrer & I. Jáuregui. 2007. Air pollution and allergens. Journal of
Investigational Allergology and Clinical Immunology, 17:
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Filgueira,
J. J. ; L. Franco-Lara, J. E. Salcedo, S. L. Gaitan & E. R. Boa. 2004.
Urapán (Fraxinus udhei)
dieback, a new disease associated with a phytoplasma in Colombia. Plant Pathology 53 (4): 520 pp.
Fraxinus uhdei (Wenz.) Lingelsh. 2021. Plants of
the World Online. Royal
Botanic Gardens, Kew. (Retrieved 3
January 2021).
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F. Wantke, M. Gotz, R. Jarish, S. Jager & M. Gotz.
2000. Ash (Fraxinus excelsior) pollen allergy in
central Europe: specific role of pollen panallergens and the major allergen
of ash pollen, Fra e 1. Allergy, 55:
923–930.
Morfín-Maciel, B.
M., I. Flores, A. Rosas-Alvarado, M. Bautista & J. R.
López-López. 2009. Sensitization pollens of oleaceae family
in a group of patients from Mexico City.
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Pasiecznik, Nick. 2016.
Fraxinus uhdei. Invasive Species
Compendium. Centre for Agriculture
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Rocha-Estrada, Alejandra,
Jorge Hernandez & Marco Antonio Alvarado Vazquez. 2008. Airborne pollen of Carya, Celtis,
Cupressus, Fraxinus and Pinus in the metropolitan area of Monterrey, Nuevo Leon,
Mexico. Annals of Agricultural and
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Wallander, Eva.
2008. Systematics of Fraxinus (Oleaceae) and evolution of
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