Medicinal Value and Floral Characteristics of Oleander

I. Origin

Apocynaceae (Nerium indicum Mill.). Also known as willow-leaf peach, half-year red, peach bamboo, pen peach. It was introduced to China for cultivation a very long time ago; as early as the Ming Dynasty's "Pingfang Pu" there are records of oleander. Although China is not the homeland of oleander, it has a cultivation history of more than 500 years to date. Growing oleander is not troublesome, so pot cultivation is very common in both the south and the north. In all areas south of the Yangtze River basin in China, it can be cultivated in the open field; in Chongqing it is close to a wild state, and can be seen everywhere. In the north it is grown in pots. When the temperature falls below 5°C, it is brought indoors; when the temperature rises above 5°C, it is taken outdoors.

II. Plant Characteristics

Evergreen shrub, can also grow into a small tree, reaching more than 500 cm in height; leaves leathery, in whorls of three, lanceolate, 16-26 cm, 1-3 cm wide, apex sharply pointed, base wedge-shaped, midrib prominent; cymes terminal, flowers peach-red, opening successively from June to October. Because the leaves resemble bamboo leaves and the flowers resemble peach blossoms, it is named oleander.

III. Ecological Characteristics

Oleander has strong adaptability; it is a sun-loving tree, likes a warm and humid climate and a sunny environment, and can also tolerate drought of no great intensity. In an environment kept at 15°C it blooms all year round, with a long flowering period; it does not tolerate waterlogging and does not tolerate severe cold. Seedlings are even less cold-tolerant than adult plants; among the common cultivars, the white-flowered one has slightly stronger cold resistance, the red-flowered cultivar is next, and the yellow-flowered one is the least cold-tolerant. When the temperature falls below 0°C, it goes dormant, so potted oleander should be overwintered at a controlled temperature of 5-10°C. It is heat-tolerant and can also tolerate drought of no great intensity. It has a very unusual ability to resist smoke, dust and various toxic gases; in an environment thick with smoke and dust, it alone blooms, and it plays a special role in purifying and protecting the environment. The roots have very strong sprouting ability. It is not strict about soil; general soil, including alkaline soil, will do, but loose, fertile, well-drained sandy loam is suitable.