The quality for which the American elm
is most loved, and which hackberry also possesses, is form.
You might wonder why someone would sow the seeds of American elm
trees that are almost certain to get sick and die in adolescence.
The leaves of the Siberian elm, much like the American elm
, grow in clusters of ellipses, iced-tea spoon size, barbed around the edges, dark green above, paler below.
If his theory is correct, he says, it could suggest strategies for controlling fungal diseases that have ravaged forests of American elms
, white pines and American chestnuts and have caused billions of dollars worth of damage to crops.
White and willow oaks, American elms
, southern magnolias, and flowering dogwoods dominate.
By the 1980s, the destructive fungus--Ophiostoma ulmi--had wiped out around 77 million American elms
that had survived years of threat from Dutch elm disease were felled and will be difficult, if not impossible, to replace.
When 1,000 mature American elms
mysteriously died in Illinois during the last decade, scientists at first suspected that the elm yellows (EY) plant pathogen was the culprit.
The National Park Service's suggestion probably surprised many of those who've mourned the loss of as many as 100 million American elms
to Dutch elm disease over the last 75 years.
Townsend has been on a quest for the last 20 years - a quest to find and develop disease-tolerant American elms
and return these prized trees to U.
Before the onslaught of Dutch elm disease, American elms
were a beloved urban tree thanks to their leafy canopy and ability to tolerate air pollution, road salt, and extremes in weather.
Denny Townsend, a research geneticist at the National Arboretum in Washington, DC, is widely known for his efforts to breed American elms
that would be resistant to the disease.
look like a vase, with arching branches that grow out from the trunk at a sharp angle.
Among the 68 trees to be cut are American elms
, sycamores, tulip poplars, a couple of Yoshino cherries, a dogwood, and one cucumber magnolia.
Efforts during the 20th century include the planting of American elms
from the Capitol to the Washington Monument by the McMillan Commission, headed by Michigan Senator James McMillan, chair of the Senate Committee on the District of Columbia, In 1912 Japan gave the United States its now-famous Japanese flowering cherries, which were planted along the Tidal Basin (see