Once one of the largest and most prevalent of the North American elm species, preferred as an ideal shade tree for urban roadsides. American Elm is especially susceptible to Dutch elm disease, and was ravaged by the fungal disease in the second half of the twentieth century. Because the tree is fast growing and bears seeds at a young age, it has been able to continue in areas where older trees have died, though the newer elms also succumb to the disease at a relatively young age. Consequently, large and mature American Elms are uncommon. Many disease-resistant cultivars and hybrids are being used to replace trees killed by Dutch elm disease.