A Comprehensive Guide to Thevetia Peruviana (Yellow Oleander)

Thevetia peruviana, commonly known as Yellow Oleander, “Cup Flower,” “Willow Seed,” or “Yellow Scholar Bamboo,” is an evergreen tree from the Dogbane family.

It can reach up to 5 meters tall, is hairless throughout, and has a brownish-bark. The leaves are leathery, linear, or lanceolate, arranged alternately along the branches.

Its large, fragrant, yellow flowers bloom in terminal corymbs. The fruit is a flattened, triangular drupe. The blooming season extends from May to December.

Native to the tropical Americas, the West Indies, and Mexico, Yellow Oleander is a beautiful ornamental tree with dense foliage and bright, long-lasting flowers, making it an excellent choice for landscaping.

Ideal for standalone or grouped plantings around buildings, in parks, green spaces, roadside areas, and near ponds, it can also serve as a hedge.

The kernels of its fruit contain a variety of cardenolides, which are used for their cardiotonic, anti-inflammatory, and diuretic properties, particularly effective in treating heart failure (especially left heart failure), paroxysmal supraventricular tachycardia, and atrial fibrillation.

I. Morphological Characteristics

The Yellow Oleander is a tree that can grow up to 5 meters tall and is hairless. Its bark is brownish with noticeable lenticels. The tree has multiple soft branches with drooping twigs and exudes a rich milky sap.

The leaves are leathery, linear or lanceolate without petioles, sharply pointed at both ends, 10-15cm long and 5-12mm wide, glossy, hairless on both sides, with margins slightly rolled back.

The midrib is recessed on the upper surface of the leaf and protrudes on the underside, with inconspicuous side veins on both surfaces.

The large, yellow, fragrant flowers form a terminal corymb, 5-9cm in length, with a 2-4cm long pedicel.

The green calyx has five triangular lobes, 5-9mm long and 1.5-3mm wide; the corolla is funnel-shaped with five hairy scales at the throat, and the lobes overlap to the left, longer than the corolla tube.

The stamens attach at the throat of the corolla tube, with filamentous filaments. The ovary is hairless, bilobed, with two ovules per chamber, and the stigma is rounded, bifurcated at the tip.

The fruit is a flattened, tri-angular drupe, 2.5-4cm in diameter, with a woody endocarp that is green and shiny when fresh, turning black when dry; containing 2-4 seeds.

The flowering period is from May to December, and the fruiting period is from August to the following spring.

II. Growing Environment

Yellow Oleander thrives in arid regions alongside roads, near ponds, and on hillside sparse woods. It grows better in moist, fertile soil and is drought-tolerant and somewhat frost-resistant.

III. Distribution Range

The Yellow Oleander is originally from the tropical Americas, the West Indies, and Mexico. It is now cultivated in tropical and subtropical regions worldwide.

IV. Growth and Propagation

Cutting Propagation

Cuttings can be done in both spring and summer. In spring, cut 1 to 2-year-old branches into segments of 15-20 cm, bundle about 20 together, and soak them in clean water such that one-third of the stem length is submerged.

Change the water of the same temperature every 1-2 days, maintaining a temperature of 20-30°C. Once adventitious roots appear at the soaked parts, the cuttings are ready for planting.

When inserting cuttings into the soil, make holes with a bamboo stick to avoid damaging the roots. Oleander’s robust regenerative abilities at the base of old stems sprout many new branches, which can be utilized for softwood cuttings in summer.

Select semi-lignified branches, keeping the top three small leaves, and insert them into the substrate. Ensure timely shading and moisture management for a high survival rate.

For layering propagation, notch or ring the part to be buried, plant it in the soil, and after about two months, separate it from the parent plant. It can be transplanted with soil the following year.

Seed Propagation

For tiny seeds that are difficult to pick up by hand or with tools, dampen one end of a toothpick and use it to adhere each seed onto the substrate surface, then cover with 1 cm of substrate.

Place the seeded pot in water, with the water level reaching half to two-thirds of the pot’s height, allowing the water to seep up slowly. For larger seeds that can be handled, place them directly into the substrate at intervals of 3 cm by 5 cm.

After seeding, cover with a substrate layer 2-3 times the thickness of the seeds. Use a sprayer or fine-mesh watering can to moisten the sowing substrate, and water again when the potting soil is slightly dry, being careful not to dislodge the seeds with a strong water flow.

V. Pest and Disease Control

Common oleander pests and diseases include leaf spot, aphids, scale insects, and sooty mold.

Leaf Spot: This primarily affects the leaves. Initially, purplish-red spots appear on the tips or edges, later expanding into circular, semi-circular, or irregular brown spots with concentric rings.

In advanced stages, the center turns white with a reddish-brown margin. In high humidity, a gray-brown mold may form on both sides of the spots, indicating the presence of the pathogen’s conidia and conidiophores.

Spray with a 1000-fold dilution of 50% benomyl wettable powder or a 600-fold dilution of 25% carbendazim wettable powder, or a 500-fold dilution of 36% methyl thiophanate suspension at the onset of the disease.

Common treatments include benomyl, carbendazim, and methyl thiophanate.

Aphids: Upon detection, use a 800-fold dilution of 40% dimethoate emulsion, or spray the plants with water steeped in cigarette butts. For minor infestations, simply brush them off. Refer to the pest control section for roses and Chenille plants for other methods.

Scale Insects: To treat branches and leaves affected by scale insects, use a 2000-fold dilution of insecticidal soap spray.

Sooty Mold: This thrives in high temperature and humidity conditions. After infection, spray with a 500-fold dilution of 50% carbendazim or a 600-fold dilution of methyl tobutrazine.

VI. Main Value

Ornamental

The yellow oleander has a graceful form with dense branches and leaves, a prolonged flowering period, and vibrant bloom colors, making it an excellent choice for garden greenery.

It is suitable for solitary or group plantings around buildings, in parks, green spaces, roadside areas, and by ponds, and can also be planted as a hedgerow.

Ecological

Yellow oleander has a strong resistance to air pollution, effectively countering toxic gases like sulfur dioxide, chlorine, and particulate matter, making it an excellent species for beautification and greening of industrial and mining areas.

Medicinal

The seeds of yellow oleander contain various cardenolides, which are effective for strengthening the heart, reducing swelling, and promoting urination.

They are notably effective for treating heart failure caused by various heart diseases (particularly effective for left-sided heart failure), paroxysmal supraventricular tachycardia, and atrial fibrillation.

The whole plant is toxic; its leaves can be used to kill maggots, flies, and mosquito larvae.