Species composition, distribution and phenological characters of pollen-allergenic plants in Beijing urban area
北京城区花粉致敏植物种类、分布及物候特征

In order to know the species composition,distribution pattern,and phenological characteristics of pollen-allergenic plants in Beijing urban area,an investigation was made,combined with literature survey and experts interviews.The results showed that within the fifth ring of Beijing,there were 99 pollen-allergenic plant species belonging to 32 genera and 19 families,among which,52 species were native plants,accounting for 52.5% of the total,26 species were introduced from other regions of China,occupying 26.3% of the total,and 21 species were introduced from foreign countries,being 21.2% of the total.The 32 genera of pollen-allergenic plants in Beijing urban area were mainly North Temperate elements,occupying 40.6%,followed by Cosmopolitan and Pantropic elements.In all functional sections of Beijing urban area,the pollen-allergenic plants were most diversified in urban parks,and had the highest proportion in street tree species.The coverage of herbs with strong pollen allergy was in the order of waste lands> gym centers and institution yards> greenbelts> parks> residential areas> squares.The blooming period of pollen-allergenic arbors in Beijing urban area was concentrated in March and April,while that of pollen-allergenic herbs was from July to September.