Pine, spruce and cedar (Pinaceae)
Flowering: March - April - May and September
In Belgium, the Pinaceae family includes 7 genera: Abies (fir), Cedrus (cedar), Larix (larch), Picea (spruce), Pinus (pine), Pseudotsuga (Douglas-fir), and Tsuga (hemlock).
All these monoecious trees with unisexual flowers and are mostly cultivars. Only pine (Pinus sylvestris) is native in Belgium.
Fir, spruce, pine and hemlock flower in May. Larch and Douglas-fir flower in March - April and cedar flowers in September.
The unisexual flowers are grouped in cones with spirally attached scales. Stamens produce huge quantities of bisaccate pollen, which despite their large size are perfectly airborne and adapted to dispersal.
The allergenic role of pinaceae seems limited. Pollen from these plants is often seen as yellow powder on surfaces such as roofs, cars, etc.