Eucalyptus
Description
Eucalyptus trees (family Myrtaceae) are fast-growing Australian evergreens. Main species planted in Spain are E. globulus (blue gum) and E. camaldulensis (river red gum), reaching 30-50 m. Bark peels in plates or strips revealing a smooth pale trunk. Juvenile leaves are opposite, sessile, glaucous; adult leaves are alternate, petiolate, sickle-shaped, coriaceous and aromatic (rich in eucalyptol). Characteristic flowers: petals fused into an operculum that detaches when opening, revealing very numerous stamens.
Habitat and distribution
Moderate presence in Madrid compared to Galicia or Portugal. Forest plantations in the south and southwest. Used as ornamental in parks and avenues. E. camaldulensis tolerates drought better. Notable specimens in Parque del Oeste and Casa de Campo.
Health impact
Variable pollination (autumn-winter for E. globulus, spring for E. camaldulensis). Low allergenicity as predominantly entomophilous (bees attracted by abundant nectar). Can cause mild rhinoconjunctivitis in sensitized patients in areas with extensive plantations.
Cross-reactivity
Low cross-reactivity. Some potential antigenic community with myrtle (Myrtus) within Myrtaceae, but without demonstrated clinical relevance.
Pollen morphology
Tricolporate pollen grain, oblate to spheroidal, 15-25 μm. Short wide colpi, sometimes with syncolpi. Granular to finely reticulate surface. Exine 1.5-2 μm. Triangular outline in polar view is characteristic.
Did you know?
Eucalyptus can reach 100 m in Australia, making them the tallest flowering trees in the world. Eucalyptus essential oil (eucalyptol/1,8-cineol) is widely used as a nasal decongestant, paradoxically to relieve the same symptoms its pollen might cause. Eucalyptus leaves are the exclusive food of koalas.
The information on this page is for educational purposes. For any questions about allergies, consult your doctor or allergist.