The Locusts - Black Locust & Honeylocust
Living here in Pennsylvania we are blessed with a huge assortment of native
trees available to us woodturners. We have thirteen beeches (which
include the oaks), nine birches, eight maples, and four legumes
(which include the locusts). Our two native locusts, the Black
locust and the Honeylocust, grow in a wide variety of locations
and conditions but can be easily distinguished from each other.
The Black locust (Robinia pseudoacacia), also known as the Yellow
locust, prefers dry sandy or rocky soil and can be found in
abandoned fields or growing along highway and railroad cuts.
The tree is medium sized, growing to 40'-80' in height with a
diameter of 1'-2'. It's compound leaves are 6"-12" long with 7
to 19 leaflets which are 1"-1 ¾" long and ½"-¾" wide. The leaves
are dark green on top and pale underneath. They have a tiny bristle
tip and have the curious habit of folding up at night. Black locusts
bark is light gray, thick and deeply furrowed into long rough
forking ridges. It has the typical pea-shaped flower of all legumes
with 5 white petals in 4"-8" long showy clusters. It's fruit is an
oblong flat 2" to 4" long pod that turns dark brown toward autumn
but stays on the tree all winter.
Black Locust - Leaf
Bark
Flower
Seed Pod
The Honeylocust (Gleditsia triacanthos), also known as the Sweet-locust
or Thorny-locust, prefers moist soils in flood plains and mixed
forests but can also be found with the Black locust in dry uplands
and waste places. This locust grows to 80' in height and 2½' in
diameter. It's compound leaves are smaller than the Black locust
and are only 3/8"-1¼" in length. The leaflets, which have a fine
wavy edge, are shiny dark green on top and yellow-green underneath
and are found in 3 to 6 pairs along the leaf. Honeylocust's bark
gray-brown or black and has long narrow scaly ridges. The trunk is
also covered with clusters of long spikes, although most of the
varieties planted in landscapes are of varieties that don't have
these spikes. It's flowers are bell-shaped with 5 petals but they
are whitish-green, as opposed to pure white of the black locust's,
and come in short clusters. The Honeylocust's seedpod is 6" to 16"
long, flat and slightly curved and twisted. When they drop off of
the tree in late autumn the pods contain a sweetish edible pulp
from which they get their name.
Honeylocust - Leaf & Flower Bark
Seed Pod
While the trees themselves may be similar, the woods are distinctly
different. Black locust has a narrow band of yellow sapwood with a
heartwood that varies from greenish-yellow to dark or golden brown
with distinct color changes between early and late wood. The grain
is straight and prominent and the woods texture is rather course.
Black locust wood weighs 58 pounds per cubic foot (pcf) green and
48 pcf dry. It is both stronger than Honeylocust wood in both
bending and impact.
Black Locust - Transverse cut
Black Locust - Tangential cut
Black Locust - Radial cut
Honeylocusts have a wide band of creamy yellow sapwood surrounding
a light red, bright cherry red or reddish brown heartwood. The
grain is also straight and often has an attractive figure. The
texture is moderately open and somewhat uneven. Honeylocust wood
is lighter than Black locust when wet weighing 61 pcf but lighter
when dry, weighing 44 pcf.
Honeylocust - Transverse cut
Honeylocust - Tangential cut
Honeylocust - Radial cut
Most turners I know prefer the Honeylocust to the Black locust.
The reasons for this are the reddish color and smoother texture.
Both make nice turning woods though. Both are moderately hard woods
so they can come off the tool with a nice finish and neither is
prone to tearout. Sanding is easy but care must be taken with
Black locust, the open texture can load up with sanding grit from
the previous paper. Be sure to blow off the piece when switching grits.
Any finish can be used with the locusts but I feel that oil based finishes tend
to do a better job of bringing out the beauty of the wood.
The locusts are plentiful and easily found in our are. While they are not stars
of the lumber world, they do make good turning woods. If you come across some
don't hesitate to give it a try, you won't be disapointed.
