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Robinia pseudoacacia

This plant has poison characteristics. See below.
Common Name(s):
Black locust, Common locust, Yellow locust
Frisia, Tortuosa
Native Plants, Poisonous Plants, Trees

The Robinia pseudoacacia, commonly called black locust, is quick growing, medium sized, suckering, deciduous tree that typically grows to 30-50’ (less frequently to 80’) tall. Although originally native to the Allegheny Mountains, it has escaped gardens and naturalized over time to cover much of the United States and southern Canada plus parts of Europe, Asia and South America. At its best, it will grow as a broadly columnar single trunk tree with a narrow oblong crown. It also will grow in suckering thickets.  Young growth on this tree has thorns.

This is a good plant for difficult sites, transplants well, and tends to reseed.  It develops shoots from roots.  It is also a legume, fixes its own nitrogen and is moderately salt tolerant.

The wood from this native is naturally rot resistant and often used to make fence posts and rails.

Regions:  Mountain, Piedmont, Coastal Plains

Seasons of Interest: 

     Leaves:       Bloom:   Spring    Fruit/Seed/Nut:  Fall

Wildlife Value:  The Black locust is a host plant for the Eastern Tiger Swallowtail, Mourning Cloak, Eastern Comma, Red-Spotted purple, and Viceroy butterflies.  The buds and catkins are eaten by birds.  It provides an excellent leaf cover for birds in wetland sites.   Bees are attracted to its flowers.

Insects, Diseases, or Other Plant Problems:  It is susceptible to locust borer (often fatal) and locust leaf miner (browns foliage). Other insect problems include caterpillars, weevils, scale and whiteflies. Possible disease problems include canker, powdery mildew, leaf spots, wood rots and verticillium wilt.

Species trees are sometimes considered to be somewhat weedy. Trees send out long underground root suckers that not only become a maintenance problem but also can disrupt nearby gardening areas.

Small branches of the Black locust fall easily during storms.  Some of its leaves yellow and fall off during times of drought.

30-50 ft.
Fragrant wisteria-like white flowers in pendant racemes (to 8” long) bloom in late spring. They are pea-like and very fragrant. The flowers are followed by smooth, flat, purple-brown seed pods (to 4-5” long).
The Black locust grows well in average, dry to medium, well-drained soils in full sun. It will tolerates some light shade, but avoid shady locations. It also tolerates a wide range of soils including sandy or nearly barren ones, but its best performance is in moist, organically rich loams.
Fine to medium
Upright; straight trunk; becomes ragged with age
Sun; tolerates a range of soil types; drought tolerant
Pendulous white wisteria-like flowers in spring; very fragrant; flat brown-black pods
Poison Part:
Inner bark, young leaves, seeds
Poison Delivery Mode:
Depression, weakness, dilated pupils, vomiting, bloody diarrhea, weak pulse, coldness of arms and legs, paleness, and shock
EDIBLE PARTS: Flowers HARVEST TIME: Only collect flowers from areas you know have NOT been treated with pesticides. SAFE HANDLING PROCEDURES: Soak flowers in warm water for several minutes to remove dirt and debris. Do not use dish detergent or any type of sanitizer. These products can leave a residue. Remove the stems from the flowers. Chop flowers and add to bread dough or to muffin/pancake batter. Whole flowers can be battered and deep fried.
Toxic Principle:
Robin, a phytotoxin; robitin, a glycoside; robinine, an alkaloid
Found in:
Forest or natural areas in dry woods; weedy in disturbed areas, roadsides, fencerows; landscape used as an ornamental flowering tree
20-35 ft.
The leaf of the Black locust is noted for its attractive alternate, compound leaves and pendant racemes of pea-like flowers. Its branches are usually armed with short paired spines (to 1.25” long). It has pinnate dark blue-green leaves, with each leaf having up to 23 lance-shaped to ovate leaflets. Leaves turn uneventful yellow in fall.
host plant, deciduous, birds, fragrant, salt tolerant, flowering, butterflies, showy

NCCES plant id: 547

Robinia pseudoacacia Robinia pseudoacacia
Robinia pseudoacacia Robinia pseudoacacia
Robinia pseudoacacia Robinia pseudoacacia flower detail
Photo by Kristine Paulus, CC BY - 2.0
Robinia pseudoacacia Robinia pseudoacacia
Photo by Thayne Tuason, CC BY-NC-2.0
Robinia pseudoacacia Robinia pseudoacacia mature form
Photo by Sandy Richard, CC BY-NC-2.0