Learn more about pollen - Elm

Elm (Species, Ulmus sp.; Family, Ulmaceae)

Elms occur naturally in the northern hemisphere temperate zones and at higher altitudes in the subtropics. Most are trees, some of which are very large and are deciduous and semi-deciduous. They are wind-pollinated and produce large amounts of pollen during September.

The planting of elms in Australia began in the first half of the 19th century when European settlers imported species from their former homelands. Owing to the demise of elms in the northern hemisphere as a result of the Dutch elm disease pandemic, the mature trees in Australia's parks and gardens are now regarded as amongst the most significant in the world. The pollen from Ulmus sp. does produce an allergic reaction in some people, and has been widely reported as a cause of hay fever in Europe and in North America.

Distribution of Dutch Elm (Atlas of Living Australia occurrence map)

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Learn more about pollen - Birch

Birch (Species, Betula sp.; Family, Fagaceae)

The main species planted across Canberra in gardens and parklands is the Silver Birch (Betula pendula), which is a medium-sized deciduous tree, typically growing up to 25 metres high. It is noted for its slender trunk, white bark, and beautiful yellow leaves in autumn. Its flowers are drooping catkins, which produce large amounts of wind-blow pollen between August and October.

In northern latitudes, birch is considered to be the most common allergenic tree pollen, with an estimated 15–20% of people with hay fever sensitive to birch pollen grains. Cross-reactivity between birch and certain foods is also a common phenomenon. People with birch pollen allergies may react to kiwi, apples, pears, peaches, plums, coriander, fennel, parsley, celery, cherries, carrots, hazelnuts and almonds.

Distribution of Birch (Atlas of Living Australia occurrence map)

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Learn more about pollen - Olive trees

Olive tree (Species, Olea europaea; Family, Oleaceae)

The Olive tree is a dense-crowned tree introduced into Australia for horticulture in the mid 19th century. In recent decades, some varieties have become aggressive woody weeds and can be found growing outside the confines of managed olive groves. The flowers are wind-pollinated and are generally producing pollen from August to October.

 

Olive trees belong to the same family as the Ash tree (Oleaceae) and it has been shown that people who are allergic to Olive trees also show an allergic response to Ash pollen (cross-reactivity).

Distribution of Olive trees (Atlas of Living Australia occurence map)

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Learn more about pollen - Privet

Privet (Species, Ligustrum lucidum; Family Oleaceae)

Privet or Ligustrum lucidum is the third member of the Oleaceae family that is associated with strong allergic reactions to pollen in some people. Privet is a shrub or tree usually growing 4 to 12 m tall and is evergreen. The flowers are wind-pollinated and are generally producing pollen from August to October.

Privet was widely planted in gardens, and was popular as a hedgerow in the early days of Canberra. Despite being removed from many gardens today it can be found as a weedy species especially in moist places and along river corridors around Canberra. 

Distribution of Privet (Atlas of Living Australia occurrence map)

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Learn more about pollen - Ash trees

Ash (Species, Fraxinus sp.; Family, Oleaceae)

Ash, a wind-pollinated tree belonging to the family Oleaceae, is distributed world-wide and has been suggested as a potent allergen source in spring time. In the Canberra region Ash trees are widely planted in gardens and parklands due to their deciduous habit and the striking display of colour during the autumn months. The peak pollen season for Fraxinus sp. is from August to September.

Ash and olive trees belong to the same family (Oleaceae) and it has been shown that people who are allergic to Ash tree pollen are also likely to be allergic to Olive tree pollen.

Distribution of Ash trees (Fraxinus sp.) from Atlas of Living Australia occurence maps

 

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