Black Locust
Robinia pseudoacacia
Copyright, Mark Brand, UConn Plant Database
John M. Randall, The Nature Conservancy
Black Locust is a medium-sized tree, growing up to 80 feet tall. It is easily recognized by its leaves and paired spines up to1/2 inch long.
Black Locusts prefer sandy or rocky soil, and are most often found in old fields, open areas, woods, and streamsides.
The leaves of this tree are pinnately compound, which means one leaf has many (7 - 19) leaflets on one main stem. Leaflets are always paired, except for the one on the end of the leaf. Leaf color is bluish-green on top, and pale underneath. The entire leaf is 6 to 12 inches long. Leaflets are oval-shaped and less than 2 inches long with no teeth and a bristle tip. At night leaflets fold up and droop.
James H. Miller, USDA Forest Service
James H. Miller, USDA Forest Service
Paul Wray, Iowa State University
Black Locust bark is light gray with deep furrows. The trunk is 1 to 2 feet wide.
Spines grow on twigs, close to where the leaves are attached. They are always in pairs.
Black Locust flowers are small, about 3/4 inch long, and pear-shaped. They each have five white petals, and many flowers grow together in a droopy cluster, 4 to 8 inches long. This tree blooms in late Spring.
If flowers get pollinated, fruits will grow. Locust fruits are pods, and Black Locust has dark brown pods up to 4 inches long. Pods stay attached to the tree in Winter, and each pod has up to 14 seeds in it.
Black Locust often grows alongside White Oak, Black Oak, Scarlet Oak, hickories, American Beech, Red Maple, Silver Maple, American Basswood, Yellow Poplar, Eastern Redcedar, American Elm, Black Cherry, White Ash, Black Walnut, Sassafras, Flowering Dogwood, Blackgum, and bluegrasses.
Black Locust flowers are pollinated by bees and hummingbirds. Seeds are eaten by Northern Bobwhite, Mourning Dove, Wild Turkey, White-tailed Deer, Eastern Cottontail, and squirrels. White-tailed Deer also eat leaves and twigs.
Many animals use this tree for cover, and cavities in Black Locust are good homes for bird and other animals, especially woodpeckers.
Bill Cook, Michigan State University
Copyright 2000, Joe DiTomaso
Paul Wray, Iowa State University
Black Locust is the host plant for Silver-spotted Skippers and Clouded Sulphur butterflies.
Black Locust does not compete well with other trees and does not tolerate shade, so it often gets crowded out. It grows very fast, but does not live long compared to most trees. It rarely lives to be 100 years old. Black Locust can survive drought and harsh winters.
This tree can send up new sprouts from roots and stumps, which may eventually turn into new trees.
Relationships in Nature:
Animals Using as Food Source
Animals Using as Shelter
Associations With Other Plants
OTHER
White-tailed Deer
Downy Woodpecker
White Oak
Ruby-throated Hummingbird Po
Northern Bobwhite
Pileated Woodpecker
Mockernut Hickory
Golden Northern Bumble Bee Po
Eastern Gray Squirrel
Black Rat Snake
American Beech
Honey Bee Po
Honey Bee
Great Crested Flycatcher
Red Maple
Clouded Sulphur H
Golden Northern Bumble Bee
Raccoon
Eastern Redcedar
Silver-spotted Skipper H
Wild Turkey
Eastern Gray Squirrel
Yellow Poplar
Buffalo Treehopper Pa
Ruby-throated Hummingbird
Virginia Opossum
Silver Maple
Eastern Cottontail
Eastern Bluebird
Black Oak
Mourning Dove
Carolina Chickadee
American Elm
Silver-spotted Skipper
White-breasted Nuthatch
Black Cherry
Clouded Sulphur
Clouded Sulphur
White Ash
Buffalo Treehopper
Bald-faced Hornet
Sassafras
Buffalo Treehopper
Flowering Dogwood
Eastern White Pine
Kentucky Bluegrass
Bigtooth Aspen
Relationship to Humans:
Black Locust seeds are poisonous to humans. Wood is used for lumber, poles, fenceposts, paper, boxes, crates, pegs, stakes, and firewood. Black Locust is planted to stop soil erosion. It is also an important plant for bee-keeping. Locust trees are planted near hives so the bees can get nectar from the flowers and make honey.
SCIENTIFIC CLASSIFICATION
KINGDOM
Plant
DIVISION
Magnoliophyta
CLASS
Magnoliopsida
ORDER
Fabales
FAMILY
Fabaceae
GENUS
Robinia
SPECIES
Robinia pseudoacacia
© 1996-2010 Fairfax County Public Schools
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