Cascabela thevetia Seeds | (syn. Peruviana)
LATIN NAME: Cascabela thevetia (syn. Thevetia peruviana)
COMMON NAME: Yellow Oleander
Plant Profile
Yellow oleander is a handsome tropical American shrub with funnel-shaped yellow flowers and a seed that can stop a human heart. It is native to Mexico and Central America and has been planted across the tropics and subtropics, where it naturalises along roadsides, in hedges and on waste ground. The plant reaches two to four metres, with glossy, narrow evergreen leaves and a succession of yellow or peach funnels at the ends of the branches through the warm months. The fruit is a black, angular drupe with a stone inside, and it hangs on the bush for months. Every part of the plant contains cardiac glycosides, and the seed is the most dangerous part: a single one has killed a child, and the sap can blind an eye. It is not related to the true oleander, though it shares both the beauty and the toxicity.
Science & Biotechnology
Cascabela thevetia belongs to the dogbane family and produces a cocktail of cardiac glycosides, chiefly thevetin A and B and peruvoside, which inhibit the sodium-potassium pump in heart muscle and, in excess, cause arrhythmias and cardiac arrest. The compounds are chemically close to digoxin and ouabain, and the plant is one of the classic sources of cardiac poisoning in the tropics, responsible for livestock deaths and for suicides in parts of Asia. It has been used in medicine in carefully controlled doses, but the margin between therapeutic and lethal is so narrow that it has largely been abandoned. The flowers are pollinated by moths, which are attracted by scent in the evening, and the fruit is eaten by few animals because of its bitterness. The species is a prolific seeder, and seed washed down drains and rivers starts new colonies far from the parent plant.
Uses & Benefits
The plant is grown as an ornamental in frost-free gardens, as a hedge, and as a container subject for a patio, and its long flowering season and tolerance of heat and drought make it useful in difficult sites. In some countries it is planted as a living fence, since livestock will not push through it. The seed and the sap have been used as a fish poison and as an arrow poison, and the plant appears in traditional medicine for skin conditions, always with the risk of a fatal mistake. It is also used in research on cardiac glycosides and on the sodium pump. In a garden with children or dogs it is a poor choice, and it should never be planted where the fruit can be picked up. Where it has naturalised it is regarded as an invasive shrub.
Growing from Seed
Soak the hard seed for a day, then sow it in a gritty mix at 25 to 30 degrees, one centimetre deep; germination takes three to six weeks. Wear gloves for the seed and wash your hands once it is sown. Grow the seedlings in full sun and well-drained soil, and pot them on until they are large enough to plant out. Water through the first dry season, then only in prolonged drought; the plant tolerates poor, sandy soil and salt spray. It is tender below about five degrees, so in cool climates it needs a conservatory or a warm wall. Prune after flowering to keep it compact, and wear gloves, since the sap irritates skin. Remove the fruit if children use the garden, and never compost the seed.
Our Take
A free-flowering tropical shrub with glossy leaves and yellow funnels, and one of the most poisonous seeds in any garden. Admire, do not taste.
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