The Bradford pear, a popular cultivar of the Callery pear (Pyrus calleryana), is an ornamental tree widely planted across the United States. It is recognized for its dense clusters of five-petaled white flowers that appear early in the spring season, often before the leaves begin to expand. Despite its visual appeal and initial popularity, this tree has gained significant notoriety for one specific trait. The blooms produce a powerful and distinctly unpleasant odor that many people find deeply offensive. This strong scent contributes to the tree’s controversial reputation.
The Unmistakable Smell of the Bradford Pear
The fragrance emanating from the dense white flowers is complex, but the common consensus is that it is distinctly foul. Many people compare the odor to decaying animal matter, specifically the smell of rotting fish. This description is so frequent that it has become the most widely accepted comparison for the tree’s spring aroma.
Other reports describe the smell using visceral comparisons, including the scent of bodily fluids, such as semen, urine, or even vomit. These strong, unpleasant associations highlight the pervasive nature of the odor when the tree is in full bloom. The intensity of this malodor can vary greatly depending on environmental factors. Warmer temperatures and higher humidity levels can increase the volatility of the compounds responsible, making the smell more noticeable.
The Scientific Explanation for the Odor
The notorious odor is caused by specific volatile organic compounds released by the flowers. The primary culprits are chemicals known as amines, including trimethylamine and dimethylamine. These molecules are highly volatile, meaning they readily evaporate and travel through the air to reach the human olfactory receptors.
Trimethylamine is noteworthy because it is a compound produced during the decomposition of plant and animal tissue. This chemical is responsible for the characteristic fishy smell associated with spoiled seafood, which explains why the human nose perceives the tree’s scent in a similar way. The release of these compounds is a biological strategy by the tree to attract specific pollinators, such as blowflies, which are drawn to scents that mimic decay or carrion.
Beyond the Smell: Context and Cultivation
The unpleasant scent is a temporary phenomenon, occurring only during the short flowering period in early spring, which typically lasts about two weeks. For the rest of the year, the tree is odorless, offering an attractive rounded or conical crown with dark green leaves.
The Bradford pear was introduced to the United States in the mid-1960s and quickly became a favorite of city planners and landscapers. The tree’s popularity stemmed from its ability to tolerate a wide range of soil conditions, its fast growth rate, and its uniform shape, making it ideal for street plantings and urban environments.
Furthermore, it was promoted as being resistant to fire blight, a serious bacterial disease affecting other pear varieties. These characteristics led to its widespread adoption, despite the drawback of the flower’s potent aroma.