is the old Roman name for the tree. 'Anagyroides' relates to the fact that it
resembles 'Anagyris', which is a Mediterranean plant, also known by scary common
names such as Stinking Bean Trefoil, Bean Clover, Stinking Wod and Mediterranean
Stinkbush. Obviously not a desirable plant to live real close with.
Propagation is either by seed, by layering and rooting hardwood cutting in the Autumn and later Winter. Cultivars are propagated by grafting or budding onto Laburnum seedling rootstock. The seeds collected in Autumn are sown the next spring and will need scarifying (e.g. treating with sandpaper to help break through the hard seed coat) to increase germination. They will be viable for 2 years if kept in dry conditions. The tree will grow up to 20 feet in 20 years and will seldom get much higher than that. It is hardy and likes a bit of lime in the soil.
Before we had a huge range of woodstains, the heart-wood of the Laburnum was often used as an Ebony substitute since it is very hard and a dark chocolate brown. The sapwood is butter-yellow.
Laburnum alpinum - Scots Laburnum
Much more common in Scotland and less so further south. Up to 10 m high. Distinguishes itself from the Common Laburnum by having almost hairless twigs, the leaves are slightly larger, the seeds are brown rather than black and the tree flowers a couple of weeks later.
Laburnum anagyroides 'Aureum' - Golden leaved Laburnum
A Laburnum with yellow leaves in the summer.
Laburnum x watereri or L. vossii - Voss's Laburnum
A hybrid between the Common and Scots Laburnum, which was grown in a Victorian garden in Surrey in 1864. It combined the best flower features of the two parents and although the pods are equally poisonous, they do not develop well and are therefore less attractive as a tempting tree fruit to children. Sometimes they are sterile.
Laburnocytissus adamii or L. adamii - Adam's Laburnum
A freak plant created by a nursery man called Adam in his garden near Paris in 1825. This is a graft-hybrid, also known as a plant-chimaera, with a thin skin of purple Broom over a core of Common Laburnum. The resulting bud died, but a nearby shoot turned out to be different from either parent and all Adam's Laburnums have been grown from this original.
Notes on the nature of Laburnum poisoning:
Every part of the tree is very poisonous and children should be warned of the danger.
"Laburnum trees should not be allowed to overhang a field used as a pasture, for when cattle and horses have browsed on the foliage and pods, the results have proved deadly.
Symptoms of poisoning by Laburnum root or seeds are intense sleepiness, vomiting, convulsive movements, coma, slight frothing atthe mouth and unequally dilated pupils. In some cases, diarrhoea is very severe and at times the convulsions are markedly tetanic." (Grieves)
"The most significant human toxins in this group ( quinoline alkaloids) are in the laburnum tree and the mescal bean. The laburnum bears golden pealike pods. Mescal bean is the seed of a small tree and often is used in ornamental jewelry. Cytisine, the alkaloid common to these plants, has nicotinelike effects on the gastrointestinal (GI) tract and the central nervous system (CNS)."
"Pathophysiology: Cytisine is similar in action to nicotine. In any isoquinoline or quinoline ingestion, GI irritation is common, and toxic ingestions almost invariably result in emesis. Onset of symptoms is rapid. GI upset and vomiting start 45 minutes to 4 hours after ingestion. CNS effects include drowsiness, weakness, loss of coordination, muscle fasciculations, seizures, coma, and mydriasis. Some anticholinergic effects, such as urinary retention, may manifest. Respiratory failure, as in nicotine poisoning, is observed in patients with severe cases. "
"The toxic alkaloids are concentrated in the pealike or brightly colored seeds in laburnum, mescal bean, and lupine. Danger to humans predominantly stems from these seeds' attractive appearance to children.
Most of the isoquinolines are noxious in smell and taste and discourage ingestion, thus human toxicity is rare. Interestingly, some domestic species tolerate ingestion of isoquinoline and other alkaloids, and humans can ingest toxic alkaloids from the milk of a poisoned animal and manifest symptoms."
(The above 3 quotes are from E-medicine, a USA medical website on www.emedicine.com/emerg/topic433.htm)
Luckily mortality in humans is very rare, hence this report in the Lancet in 1979: "In an average summer over three thousand children are admitted to hospital in England and Wales because of laburnum poisoning. It is suggested that laburnum is not as dangerous as has been thought and that many of these admissions are unnecessary."
Nevertheless anyone who has eaten Laburnum seeds should be taken immediately to an emergency department, where activated charcoal may be administered to soak up the poison and other drugs and treatment may be administered as required for possible seizures or respiratory failure.
Remember that as little as two seeds can suffice to poison a child and the tree should therefore never be planted near children's playgrounds.