Callery Pear
The Callery pear (from the Pyrus calleryana tree, often called Bradford pear) is the most infamous for this trait. Its clusters of small white flowers bloom profusely in spring, emitting a strong, musky, bleach-like or fishy semen scent from compounds like trimethylamine and spermine.
The tree produces tiny, hard, inedible pear fruits that birds spread, making it invasive in many areas. Widely planted ornamentally for its shape and blooms, but the smell has led to bans in some U.S. states.
Evergreen Pear
The evergreen pear (Pyrus kawakamii) shares a close relation to the Callery and produces similar white flower clusters that give off a pungent semen-like aroma, often described as fishy or chemical.
This semi-evergreen tree holds its leaves longer in mild climates and yields small, round, inedible pears that add to its ornamental appeal despite the notorious bloom scent. It’s popular in warmer urban landscapes.
Carob
The carob tree (Ceratonia siliqua) has male flowers that distinctly smell like human semen, thanks to amine compounds. These small, clustered blooms appear in catkin-like racemes, primarily on male or dioecious trees.
The tree is prized for its long, edible pods (used as chocolate substitute), which develop after pollination and are sweet when ripe—ironic given the flower odor. It’s drought-tolerant and common in Mediterranean regions.
Chestnut
Chestnut trees (Castanea species, like American or European) have catkin flowers that can emit a semen-like odor from 1-pyrroline and related compounds. The long, creamy-white male catkins are noticeable in summer, attracting pollinators with this unusual scent.
The tree produces spiky husks containing edible chestnuts—sweet and nutritious nuts valued worldwide. The flower aroma is less infamous than others but documented in botanical studies.
Tree of Heaven
Tree of heaven (Ailanthus altissima) earns the nickname “cum tree” from its pollen-heavy male flowers, which release a strong, distinctive semen-like smell.
The small greenish blooms form in large panicles, contributing to its invasive spread via wind-dispersed samara “fruits” (winged seeds). No edible fruit here, but the tree grows aggressively and is often reviled for both its odor and weedy nature.