Sunday, May 20, 2007

Black locust (Robinia pseudoacacia)

Black locusts get no respect. People have largely quit planting them. The trees plant themselves, soldiering on, spreading both by seed and by shoots from their roots. They’re often considered weeds. Capable of fixing nitrogen, black locusts don’t need fertile soil and can grow almost anywhere. (1) The reason we no longer plant them in any numbers is their terrible problem with borers, a very difficult to control insect pest that can cause them devastating damage.

The black locusts are in bloom now all over Plainfield. The beautiful, hanging creamy white panicles of these handsome American natives are quite eye-catching and resemble wisteria. They have the added bonus of fragrance. Aficionados of artisanal honeys might recognize the blooms as the source of acacia honey. The bark is also quite attractive. Deeply furrowed and distinctive, it makes the trees easy to spot even when they are bare of leaves.

Black locust wood used to be highly valued for fence posts. The very dense wood is resistant to rot in contact with the ground, a fact that led to the species' being spread around the country by humans from its native range in the vicinity of the southern Appalachian Mountains. The Jamestown colonists built hovels using black locust posts as their first habitations in 1607. The posts were noted by a visiting English naturalist to still be sound 100 years later. (2) The wood was also valued as fuel. A cord of black locust wood has the same energy content as a ton of anthracite coal. (3)

Drive or walk around and have a look. Most neighborhoods have some of these trees. An attractive example of black locust that is covered in blooms right now is in the front yard at 1400 Prospect Avenue.

Also in bloom now: tulip trees and horse chestnuts. Tulip tree blooms don't shout out their presence. You have to look for them because their pale yellow color blends in with the foliage. It's worth looking. The superb specimen at 443 Stelle Avenue merits a visit. Paulownias are also in bloom (if you can find one). There is a Paulownia (empress or princess tree, one of the symbols of the Japanese imperial throne) next to the garage at 1030 Sherman Avenue. Spectacular pale lavender blooms on a tree that, in this country at least, is not much valued.

(1) Nitrogen-fixing plants have a symbiotic relationship with certain soil bacteria that allows the plants to use atmospheric nitrogen. Unlike most plants, they don't require that their soil contain nitrogen compounds.
(2) Donald Culross Peattie, A Natural History of North American Trees, Houghton Mifflin 2007.
(3) Charles Fergus, Trees of Pennsylvania and the Northeast, Stackpole Books 2002.

Copyright Gregory Palermo

Monday, May 7, 2007

American Elm

Once the most common street tree in the northeastern United States, the American elm has become something of a rarity. This beloved native was almost wiped out by Dutch elm disease in the middle of the last century. One of the early victims of globalization, the elm was attacked by a foreign fungus: Dutch elm disease was carried to the U.S. by elm bark beetles in imported logs. The disease continues to destroy elms to this day. When you see a mature elm, it’s hard to know whether it has survived because it is disease-resistant or because it is lucky enough not to have been attacked.

An American elm is easily recognizable. Its doubly toothed leaves are unusual for being asymmetrical. The tree usually has a distinctive vase shape. The gentle undulation of its limbs as they reach for the sky gives the American elm a sinuous grace that is unmatched by any other tree. Those characteristics are exemplified by the elm at the Drake House Museum on West Front Street.

The American elm at the rear of 116 Watchung Avenue (visible from Parking Lot 6 on Second Street between Park and Watchung Avenues) was recently cited by the City as a specimen tree at the 2007 Arbor Day celebration. The tree measures 47 inches in diameter at breast height. I estimate its age at 100 years.

The two elms on Park Avenue near Muhlenberg Hospital (1267 and 1303 Park Avenue), have a more pronounced limb curvature than one thinks of as classic. When I drive by those elms in winter, their exaggerated curves against the sky always bring to mind dancing girls.

The best example of a local American elm that I know is in the 3800 block of Park Avenue in Edison. Its arching limbs reaching across the street are visible from a quarter mile in either direction. The elm is on the left side of the road when one is heading away from Plainfield.

Seeing this beautiful tree I understand very easily why people once planted elms to the point of overabundance. Sadly, the huge numbers of those elms and their close proximity to each other made it easy for Dutch elm disease to spread from one tree to the next. Michael Dirr, author of the plant bible known as the Manual of Woody Landscape Plants draws a lesson from the story of the elms: “The extensive use of one tree such as the American elm is an example of foolhardy landscaping. The tree is enormously ornamental and was overplanted. The diseases caught up with the tree and the results were disastrous. Unfortunately, people do not seem to learn by their mistakes and now Honeylocust, Bradford Pear, Green Ash, Red Maple, and Planetree are being used in wholesale fashion for cities, residences, and about everywhere. I strongly urge a diversified tree planting program encompassing many different species and cultivars.”

I have included photographs of every mature Plainfield elm that I know. I would be glad to hear about others. I am also on the lookout for dawn redwoods and for outstanding examples of white oaks and red maples (Acer rubrum).

Copyright Gregory Palermo