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

1 comment:

Anonymous said...

Found this nice write up googling after a developer leveled the amazing 60-80 foot Black Locusts in my back yard. They smelled amazing and flowered all spring.

They were canopy filling trees with only top leaves. I really grew to love them before I lost them.

and vids of them on you tube

Thanks for teaching me more about them.