Robinia pseudoacacia - Black locust

Family: Pea - Fabaceae

Identification
Robinia pseudoacacia is a deciduous Tree growing to 25 m (82ft) by 15 m (49ft) at a fast rate.
It is hardy to zone (UK) 3. It is in flower in June, and the seeds ripen from Nov to March. The flowers are hermaphrodite (have both male and female organs) and are pollinated by Bees.It can fix Nitrogen.
It is noted for attracting wildlife.[PFAF]

Suitable for: light (sandy), medium (loamy) and heavy (clay) soils, prefers well-drained soil and can grow in nutritionally poor soil. Suitable pH: acid, neutral and basic (alkaline) soils. It cannot grow in the shade. It prefers dry or moist soil and can tolerate drought. It can tolerate atmospheric pollution.[PFAF]

Introduction
Black locust is deciduous weedy tree species in the Pea Family (Fabacaea). It is native to the southeastern United States but has been introduced across the US and parts of Canada where it has been used both ornamentally and in land reclamation (USDA 2010). In BC, it has escaped and naturalized in the southern part of the province in disturbed areas and forest edges. It is a tall (to 25 m), nearly glabrous, deciduous tree that reaches heights of 80 ft. It has dark-brown, deeply furrowed bark and prickly branches with alternate, large, and pinnate leaves that have (7) 11 to 21 leaflets. The white flowers are very fragrant, producing drooping, smooth, shiny pea pods that contain 4 to 8 seeds and remain on the branches in winter. It reproduces from seeds, suckers, and stump sprouts and can form thickets (Global Invasive Species Database 2010). Across its range, it is particularly invasive in "dry and sand prairies and oak savannas" (Global Invasive Species Database 2010). View more photos of this species.[E-flora]

• Origin Status: Exotic [E-flora]
• General: Fast-growing, spiny tree with thick, furrowed bark, to 25 m tall, often spreading by underground suckers. [IFBC-E-flora]
• Habitat/Range: Mesic disturbed areas and forest edges; rare horticultural escape in SW and SC BC; native to E U.S. [IFBC-E-flora]

Hazards

All parts of the plant (except the flowers) and especially the bark, should be considered to be toxic[4, 65, 76]. The toxins are destroyed by heat[65]. [PFAF] The bark contains Robin, a toxin similar to Ricin.[PDBHM] The bark, seeds, and leaves are toxic. Robin, a plant lectin (toxalbumin) related to ricin.[HPIP Shih] Ricin, a toxalbumin inhibits protein synthesis [PTH] Poisoning from this tree is potentially serious, but exceedingly uncommon. Effects depend upon the amount of toxin exposure and include nausea, vomiting, abdominal cramping, diarrhea, and dehydration.Variations in the severity of toxicity may be related to the degree to which the seeds are ground or chewed before ingestion.Parenteral administration (such as by injection or inhalation), or perhaps a large ingestion, may produce lifethreatening systemic findings, including multisystem organ failure, even with small exposures.[HPIP Shih] Toxicity may occur with as little as one bean. Toxicity is variable; related to variations within plants and GI absorption, seed has hard coat; rupture makes toxin available; symptomatic patients should be hospitalized; asymptomatic patients that have received early thorough decontamination may be observed at home. Toxic part: Bark, seeds, and leaves are toxic.[PTH]

• Poisonings: Three cases of the poisoning of children by- the root have been recorded. (Ann. Ther., I860, 64.) Z. T. Emery (N. Y. M. J., Jan. 22, 1887) reports the poisoning of thirty-two boys from chewing the inner bark of the tree. The symptoms in the mildest cases were vomiting and flushed face, dryness of the throat and mouth, and dilated pupils. In the severest cases, to these were added epigastric pain, extremely feeble, intermittent heart action, and stupor.[Remington USD20]
  
• Livestock Poison: The root and inner bark are poisonous to cattle. The leaves, on the other hand, are said to offer a wholesome food for foraging animals. [Remington USD20]
• Toxicology: The protein toxins derived from these plants work specifically by inhibiting the function of ribosomes, the subcellular organelle responsible for protein synthesis. The toxins typically have two linked polypeptide chains. One of the chains binds to cell-surface glycoproteins to allow endocytosis into the cell. The other chain upon cell entry binds the 60S ribosomal subunit and impairs its ability to synthesize protein.[HPIP Shih] The toxic constituents in R. pseudoacacia are not well defined, but at least some of the adverse effects probably result from toxic glycoproteins (lectins). Compounds isolated from this species include lectins (robin, robitin, phasin), robinlin (C11 - homomonoterpene)1 and triterpene glycosides (robiniosides A - J, sophora flavoside II).[2,3] Analysis of an ethanolic extract of R. pseudoacacia indicated that the major constituent was robinetin … with smaller amounts of myricetin and quercetin as measured by nuclear magnetic resonance and mass spectroscopy.[4] The toxic constituents probably contain heat - labile proteins.[TNS] In medicine, the term "labile" means susceptible to alteration or destruction. For example, a heat-labile protein is one that can be changed or destroyed at high temperatures.[Wiki-1]
• Toxic Effects: Clinical manifestations depend largely on the route of exposure. Following ingestion, local gastroenteritis produces diarrhea and abdominal pain. Because the seed coat of many toxalbumin containing seeds is tough, chewing is generally a prerequisite for toxicity. Absorption of toxin into the systemic circulation allows widespread distribution and multisystem organ failure. Parenteral administration via injection similarly produces diffuse organ dysfunction. Following inhalation of aerosolized toxin, localized pulmonary effects are of greatest concern, although systemic toxicity is possible. Depending on the dose and route administered, the development of findings may be delayed.[HPIP Shih]
  Death from multisystem organ failure is best prevented through aggressive support of vital organ function and prevention of infection. Work is progressing on the use of antiricin antibodies, but it is not in current clinical use.[HPIP Shih] In addition to vomiting and diarrhea, late phase toxicity due to cytotoxic effects on liver, CNS, kidney, and adrenal system. Acutely causes irritation to oropharynx, esophagus, and GI tract; may cause hemorrhage and tissue sloughing. Acute effects occur within 8 hours; late phase complications delayed by 2-5 days possibly with asymptomatic phase in between [PTH]
• Treatment: Activated charcoal may be useful; consider using osmotic cathartic despite hyperactive bowel as decreased exposure to mucosa may be beneficial, follow fluid and electrolyte status closely if symptomatic; if symptomatic, maintain high urine flow; consider alkalinization to prevent hemoglobin crystallization in severe poisonings; guaiac emesis, stool, follow fluid and electrolyte status; check hematologic parameters in severe poisoning, hepatic enzymes. [PTH] Cases associated with gastrointestinal effects need to be assessed for signs of dehydration and electrolyte abnormalities. Activated charcoal should be administered. Intravenous hydration, antiemetics, and electrolyte replacement may be necessary in severe cases, particularly those involving children. Consultation with a Poison Control Center should be strongly considered.[HPIP Shih]
  

Edible Uses

• Seeds: The seeds of the Locust Tree were gathered and cooked by the Indians (with meat, it is said). They are slightly acid and oily and may be used as we use peas and beans. They lose acidity on boiling and become a pleasant nutritious food. The pods could be dried and preserved for winter use when other vegetable food was scarce. Often they are produced in great abundance and hang on the tree until the next spring, thus giving this food a long sea- sonal range. [EWP] Seed - cooked[2, 55, 61]. Oily[161]. They are boiled and used like peas[183]. After boiling the seeds lose their acid taste[213]. The seed is about 4mm long and is produced in pods up to 10cm long that contain 4 - 8 seeds[82]. A nutritional analysis is available[218].[PFAF]
• Seedpods: I have also seen the statement that the pods when young and tender were eaten by the native tribes [EWP]
  Young seedpods - cooked[105]. The pods contain a sweetish pulp that is safe to eat and is relished by small children[201]. (This report is quite probably mistaken, having been confused with the honey locust, Gleditsia spp[K].) A strong, narcotic and intoxicating drink is made from the skin of the fruit[13].[PFAF]
• Flowers: Flowers - cooked. A fragrant aroma, they are used in making jams and pancakes[7, 183]. They can also be made into a pleasant drink[183].[PFAF]
  Robinia pseudoacacia L. H2 (7 loc.) – flowers, raw, also in jams (Oborniki, Wp) and cakes in Nowe Kramsko (Zielona Góra, Lb); LN: akacja, akacki, myszki.[Luczaj]
  Children also ate, chewed, or sucked as a sweet the flowers of many plants belonging to different families. One of the most commonly sought species for this reason was Robinia pseudoacacia (eight reports), a naturalized North American tree whose flowers, called ‘pany quesillo’ (bread and cheese), were eaten raw as a snack.[Tardio] The flowers are delicious raw, with a flavor similar to pea pods dipped in honey. They're great just stripped off the central stalk and thrown into a salad. But my favorite way of using them is to mix them with fritter batter and fry in some vegetable oil until browned on both sides. ...You can also freeze the raw flowers for later use, and they'll be at least as sweet as they were when fresh. (Russ Cohen)[WildFoodForum]

Other Uses

The bark contains tannin, but not in sufficient quantity for utilization[223]. On a 10% moisture basis, the bark contains 7.2% tannin and the heartwood of young trees 5.7%[223].[PFAF]

• Wood: The wood of the locust tree is hard, strong, very durable in contact with the soil, and makes excellent fuel. [EWP] Wood - close-grained, exceedingly hard, heavy, very strong, resists shock and is very durable in contact with the soil. It weighs 45lb per cubic foot and is used in shipbuilding and for making fence posts, treenails, floors etc[4, 7, 11, 13, 46, 61, 82, 149, 171, 227]. A very good fuel[82], but it should be used with caution because it flares up and projects sparks[226]. The wood of Robinia pseudoacacia var. rectissima, the so called 'Long Island' or 'Shipmast' locust, has a greater resistance to decay and wood borers, outlasting other locust posts and stakes by 50 - 100%[269].[PFAF]
• Papermaking: The bark is used to make paper and is a substitute for silk and wool[13].[PFAF]
• Dye: A yellow dye is obtained from the bark[223]. Robinetin is a strong dyestuff yielding with different mordants different shades similar to those obtained with fisetin, quercetin, and myricetin; with aluminum mordant, it dyes cotton to a brown-orange shade[269].[PFAF]
• Oil: A drying oil is obtained from the seed[2, 7]. An essential oil is obtained from the flowers. Highly valued, it is used in perfumery[7, 57, 100].[PFAF]

Medicinal Uses

Febrifuge[13, 46]. [PFAF] This well-known indigenous tree has a place in the materia medica of the eclectics. [Remington USD20]

• Flowers: The flowers are antispasmodic, aromatic, diuretic, emollient and laxative[218]. They are cooked and eaten for the treatment of eye ailments[218]. The flower is said to contain the antitumor compound benzoaldehyde[269].[PFAF] Flowers— diuretic, antispasmodic.[Khare IMP]
• Root & Bark: The inner bark and the root bark are emetic, purgative and tonic[4, 7, 218, 257]. The root bark has been chewed to induce vomiting, or held in the mouth to allay toothache[222, 257], though it is rarely if ever prescribed as a therapeutic agent in Britain[4]. [PFAF]' The root is used in a hot bath or sweat bath.[Huron Smith]
  The bark of the trunk is used as a seasoner to give flavor to other wild medicines. That this is a dangerous practice is held by white physicians who cite records of poisoning by the inner bark. It will also agglutinate and clot the blood corpuscles of certain animals and possesses, for the human body, strong emetic and purgative properties.[HuronSmith Menomini]
• Seedpod: The fruit is narcotic[13]. This probably refers to the seedpod. [PFAF]
• Leaves: The leaves are cholagogue and emetic[7]. The leaf juice inhibits viruses[218]. [PFAF] Leaves—laxative, antispasmodic (an infusion is prescribed in digestive disorders).[Khare IMP]

Pharmacology

Phytochemicals

Piperonal is extracted from the plant, it is used as a vanilla substitute[105]. No further details.[PFAF]

Nutritional

Use of Related Sp.

ROBINIA LOCUST

4 species: temperate United States to subtropical southwestern United States, Mexico. (J. Robin (1550–1629), V. Robin (1579–1662), French botanists who introduced genus to Eur) [Lavin et al. 2003 Syst Bot 28:387–409] Robinia hispida L. spreading from planted plants in Sacramento River Delta, potentially naturalized.
Unabridged references: [Lavin & Sousa 1995 Syst Bot Monogr 45:117–124][Jepson]

Cultivation

Pests: The greatest enemy of the tree is the locust borer, which is very common in the East and has practically destroyed many fine groves. [EWP]
Stabilization: Trees sucker freely, especially if coppiced, and they can be used for stabilizing banks etc[200, 226].[PFAF]

Aggressive surface roots possible. Succeeds in any well-drained soil, preferring one that is not too rich[1, 200]. Succeeds in dry barren sites, tolerating drought and atmospheric pollution[60, 200]. Succeeds in a hot dry position. The plant is reported to tolerate an annual precipitation in the range of 61 to 191cm, an annual temperature in the range of 7.6 to 20.3^oC and a pH of 6.0 to 7.0[269]. A fast-growing tree for the first 30 years of its life[188, 269], it can begin to flower when only 6 years old, though 10 - 12 years is more normal[229]. The flowers are a rich source of nectar and are very fragrant[82] with a vanilla-like scent[245]. The branches are brittle and very liable to wind damage[200]. When plants are grown in rich soils they produce coarse and rank growth which is even more liable to wind damage[11, 200]. The plants sucker freely and often form dense thickets, the suckers have vicious thorns[226]. There are some named varieties selected for their ornamental value[188], some of these are thornless[226]. Any pruning should be done in late summer in order to reduce the risk of bleeding[200]. The leaves are rich in tannin and other substances which inhibit the growth of other plants[13]. A very greedy tree, tending to impoverish the soil[13]. (Although a legume, I believe it does not fix atmospheric nitrogen[K]) A very good bee plant[7, 13, 20, 201]. This species is notably resistant to honey fungus[88, 200]. [PFAF]

Propagation
A short stratification improves germination rates and time[80]. Prick out the seedlings into individual pots when they are large enough to handle and grow them on in the greenhouse for their first winter. Plant them out into their permanent positions in the following summer. Other reports say that the seed can be sown in an outdoor seedbed in spring[78, 98]. The seed stores for over 10 years[113]. Suckers taken during the dormant season.[PFAF]
Panicles of white, pealike flowers in May turn to brown pods by fall, each containing four to ten black seeds, each about 1/4 inch long. Black locusts may bear as young as six years, but years of abundant pod production are periodic.
Collecting Seeds: Collect the pods in fall white they’re still whole.
When to Plant: Plant seeds in fall, soon after they drop.
Breaking Dormancy: The impermeable seed coats can cause dormancy, so nick or abrade the seeds and treat them with boiling water before planting, or use acid scarification for about ten minutes to one hour.
How to Plant: Cover them with about 1/4 inch of soil, sand, or sand and sawdust. Raised beds make transplanting easier.
Remarks: Locusts volunteer readily in our garden and hedgerows, so you’ll probably get plenty of trees if you plant seeds casually in sunny places where you might like to have then growing.[HSSH Bubel]

References

• [Duke]Accessed Feb 23,2015, http://sun.ars-grin.gov:8080/npgspub/xsql/duke/plantdisp.xsql?taxon=863
• [E-flora] Accessed Feb 23, 2015, http://linnet.geog.ubc.ca/Atlas/Atlas.aspx?sciname=Robinia%20pseudoacacia&redblue=Both&lifeform=2
• [Huron Smith]HURON SMITH'S ETHNOBOTANYOF THE HOCAK (WINNEBAGO), KELLY KINDSCHER AND DANA P. HURLBURT
• [Jepson]2013. ROBINIA LOCUST, Matt Lavin, Duane Isely & Elizabeth McClintock in Jepson Flora Project (eds.) Jepson eFlora, http://ucjeps.berkeley.edu/cgi-bin/get_IJM.pl?tid=9412, accessed on Feb 21 2015
• [Luczaj]Archival data on wild food plants used in Poland in 1948, Łukasz Łuczaj, Journal of Ethnobiology and Ethnomedicine 2008
• [PFAF] http://www.pfaf.org/user/Plant.aspx?LatinName=Robinia+pseudoacacia Robinia pseudoacacia www.pfaf.org, accessed Dec 2, 2014
• [Tardio]Ethnobotanical review of wild edible plants in Spain, JAVIER TARDÍO, MANUEL PARDO-DE-SANTAYANA and RAMÓN MORALES, Botanical Journal of the Linnean Society, 2006
• [Wiki] Accessed Feb 23, 2015
  [1]http://en.wikipedia.org/wiki/Lability