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Black Locust (Robinia pseudoacacia)

Fruit Fruit

Leaf Leaf

ID Key

Common Name: Black Locust
Scientific Name: Robinia pseudoacacia
Other Names: False Acacia

Leaf: Compound (pinnately), alternate, deciduous, 20-30cm long with each leaflet 3-5cm long; 7-19 leaflets per leaf with a terminal leaflet present; leaflets oval, dull green, smooth-edged.
Flower: White with a yellow blotch on the upper petals, showy, fragrant; in loose, drooping clusters 10-14cm long with each flower 1.5-2.5cm wide; flowers in early summer about 1 month after the leaves unfold; insect-pollinated.
Fruit: In flat pods 7-10cm long (about the size and shape of a pea pod); husk reddish-brown to black (after ripening), thin-walled, hairless; seeds dark, bean-like, 3-5mm long, hard, 4-8 per pod with hard impermeable coat; remains on tree throughout winter.
Twig: Twigs reddish-brown, slender, zigzagged, brittle, smooth; leaf scars triangular to 3-lobed with 3 vein scars; buds tiny, clustered in 3 or 4, overed with overlapping scales, form underneath the leaf base; no terminal bud.
Bark: Young bark smooth with conspicuous lenticels; Mature bark deeply furrowed, scaly, thick, dark brown.
Wood: Very strong, heavy, hard, decay-resistant.

Facts About This Tree:
1. Black locusts are medium size trees growing up to 25m high and 60cm in trunk diameter. Lives about 90 years.
2. Native to eastern United States, black locusts are widely planted and naturalized in much of Southern Canada.
3. The decay-resistant wood of black locust was once used for railway ties, fence posts, stakes and pilings and was exported to England for shipbuilding.
4. Although the seeds are toxic to humans, birds and small mammals eat them with impunity.
5. Like most members of the pea family, black locust has root nodules containing nitrogen-fixing bacteria. Soils under black locust have elevated levels of phosphorus and calcium, and its leaf litter contains more nitrogen than that of most native trees.
6. Black locust has been used to reforest waste areas such as mine spoils where few other trees could survive.
7. Its root suckers produce dense colonies that help prevent erosion. The strong root networks have even been used to support dikes.
8. Although toxic to cattles, black locust is raised specifically to feed domestic goats in Pakistan and New Zealand.

Lat, Long: 43.78377, -79.5919
Diameter (DBH): 35.7 cm
Last Year Modified: 2015
Carbon Stored in this Tree: 262.67 kg of C
Equivalent CO2: 963.03 kg of C

Find more trees in Woodbridge.

Reference
1. Linda Kershaw. 2001. Trees of Ontario. Edmonton, AB Canada. Lone Pine Publishing
2. Farrar, J. L. 2007. Trees in Canada. ON. Canadian Forest Service.
3. Michigan Department of Natural Resources. 2012. Invasive Species – Best Control Practices – Black Locust. retrived on Aug 2014 from http://mnfi.anr.msu.edu/invasive-species/BlackLocustBCP.pdf
4. Photo Credit: Daniel J. Kim; n376_w1150 by Biodiversity Heritage Library – biodiversitylibrary.org/page/28548104; Robinia pseudoacacia* – Gewohnliche Robinie by Nuuuuuuuuuuul via Flickr – https://flic.kr/p/c4ScEL; Robinie_Samen_DSC_0753 by Rudolf Schafer via Flickr – https://flic.kr/p/dVheNt; Black Locust by Dendroica cerulea via Flickr – https://flic.kr/p/ehsoif
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