Betula pendula (as "B. oycoviensis") was previously listed on the Red List as vulnerable, though it is now considered a synonym of "Betula pendula" subsp. "pendula". "Betula szaferi" was previously considered extinct in the wild on the Red List, but is now considered a form of "B. pendula" with the presence of a mutant gene, causing it to grow weakly and fruit heavily. Silver birch is often planted in parks and gardens, grown for its white bark and gracefully drooping shoots, sometimes even in warmer-than-optimum places such as Los Angeles and Sydney. In Scandinavia and other regions of northern Europe, it is
Pterocarya fraxinifolia appear in April, the male catkins thick and green, 7.5 – 12.5 cm long, the females longer with less dense flowers, bearing red styles forming fruiting catkins 30 – 50 cm long, the green, winged, nuts approximately 1.8 cm wide. The species is fast growing and grows best on flat ground or shallow slopes near river banks and in deep moist soils. The climate associated with the distribution of this tree includes mild winters and mild humid summers. It generally grows in mixed stands with other species and rarely grows in pure stands. Fossils of "Pterocarya fraxinifolia" have been described