Parts of eastern and northeastern North America are home to plants that could be transferred successfully to Finland. The first plants from North America were collected by a Finnish priest, explorer and botanist Pehr Kalm (1716–1775), a student of Swedish botanist Carl von Linné, in the 1750s.
This section features North American broadleaved trees and shrubs with their unique features and often decorative leaves. Plants in the eastern parts of North America generally require a high degree of accumulated temperature, which is used to describe the importance of heat during the growing season. Calculating the accumulated temperature begins when the average temperature exceeds + 5 °C. The annual accumulated temperature is the sum of the average temperatures on days warmer than this.
Plants in North America bud slowly in spring, but can grow late into the autumn. They often have good frost resistance and are therefore well suited to the Finnish climate. In addition to the exotic species that grow in the rich groves of the arboretum, rare domestic grove plants can also be found, such as dog’s mercury, yellow anemone and wych elm.