North American hardwood tree species, such as alder (Alnus spp.), ash (Fraxinus spp.), basswood (Tilia spp.), beech (Fagus spp.), birch (Betula spp.), black cherry (Prunus seratina), black walnut (Juglans nigra), black willow (Salix nigra), elm (Ulmus spp.), hackberry (Celtis occidentalis), hard maple (Acer spp.), hickory (Cazya spp.), oak (Quercus spp.), pecan (Cazya spp.), sassafras (Sassafras albidium), sweetgum (Liquidambar styraciflua), sycamore (Platanus spp.), and yellow poplar (Liriodendran tulipifera), are important resources for the forest products industry worldwide and to the international trade of lumber and logs. The economic market for these tree species can be very high. Many of these hardwood species are also planted in the urban landscape, plantations, or orchards for seed or nut production.
Pijut, Paula M.; Woeste, Keith E.; Michler, Charles H. 2011. Promotion of adventitious root formation of difficult-to-root hardwood tree species. In: Janick, Jules, ed. Horticultural Reviews. 38: 213-251.