Latest summary of the origin and distribution of rhododendrons

Rhododendron, also known as yingshanhong and shanshiliu, is an evergreen or semi-evergreen shrub, a typical indicator plant of acidic soil in central-south and southwest China, and because of its bright red corolla it is a famous flowering plant with high ornamental value, cultivated in parks all over the world. Now let us take a look at the origin, distribution and growing environment of rhododendrons!

Origin and distribution of rhododendrons

Rhododendrons come from Jiangsu, Anhui, Zhejiang, Jiangxi, Fujian, Taiwan, China, Hubei, Hunan, Guangdong, Guangxi, Sichuan, Guizhou and Yunnan in China. In China, Jiangxi, Anhui and Guizhou have the rhododendron as their provincial flower, and as many as seven or eight cities, including Changsha, Wuxi, Jiujiang, Zhenjiang, Dali, Jiaxing and Ganzhou, have designated it as their city flower. In May 1985, the rhododendron was rated sixth among China's top ten famous flowers.

The origin environment of rhododendrons

1. Rhododendrons grow at an altitude of 500-1200 m in mountain open thickets or under pine forests. They like acidic soil and grow poorly, or even not at all, in calcareous soil. Therefore, soil scientists often use rhododendrons as an indicator crop of acidic soil.

2. Rhododendrons prefer a cool, moist, well-ventilated semi-shaded environment. They fear both intense heat and severe cold. The optimum growing temperature is 12°C to 25°C. When the summer temperature exceeds 35°C, the new shoots and new leaves grow slowly and the plant enters a semi-dormant state.

3. In summer, protect them from the sun and provide shade; in winter, pay attention to keeping them warm and protecting them from the cold. Avoid direct exposure to the scorching sun; they are suitable for growing under diffused light of low intensity. If the light is too strong, the tender leaves are easily scorched, the edges of both new and old leaves burn, and in severe cases the plant may die.

4. For rhododendrons cultivated outdoors in winter, measures should be taken to protect them from the cold so that they can overwinter safely. Among ornamental rhododendrons, the Western rhododendron has the weakest cold resistance, and frost damage easily occurs when the temperature drops below 0°C.

Main varieties of rhododendrons

There are more than 900 species of Rhododendron in the world. Over the past century or so, nearly ten thousand horticultural varieties have appeared worldwide. Since the 1920s-1930s, China has introduced rhododendrons from Japan, Europe and the United States for cultivation, and a small number of new varieties have also been bred through hybridization. Rhododendrons are divided into the "five major" strain groups, namely the spring rhododendron strain, the summer rhododendron strain, the Western rhododendron strain, the Eastern rhododendron strain and the alpine rhododendron strain.

1. Spring rhododendron: The spring rhododendron flower originated in China, and is also distributed in the mountains of the Malay Peninsula and southern Asia. The mountainous areas of Sichuan, Yunnan and Guizhou in China are extremely rich in evergreen rhododendron species, while deciduous rhododendrons are distributed from the northeast to south China. Natural communities are distributed in high mountains and grow on shady slopes; they are semi-shade plants. They like to grow in a cool climate with high air humidity and acidic soil, and also tolerate poor soil, but not waterlogging.

2. Summer rhododendron: In spring it first grows branches and leaves, then blooms in early May-June, hence the name summer rhododendron. Its main parents are said to be Rhododendron indicum and Rhododendron obtusum.

3. Eastern rhododendron: The Eastern rhododendron is a variety of Japan's Rhododendron obtusum and its numerous hybrid descendants. It was introduced from Japan, and is called Eastern rhododendron to correspond with the Western rhododendron. The Eastern rhododendron blooms in spring, and in some places it is classified as a spring rhododendron.

4. Western rhododendron: Because of its gorgeous flowers, the Western rhododendron is a very popular type, especially the Belgian rhododendron. Since it is a horticultural cultivar hybridized in Europe and the United States, it is called Western rhododendron, also known as xidujuan. After Japan introduced it in 1892, the names of Western rhododendron varieties were translated into Japanese, so those introduced into China from Japan still use the Japanese translated names. At the same time, China has further hybridized Western rhododendrons and bred a number of new varieties, so there are about 200-300 Western rhododendron varieties in China.

5. Alpine rhododendron: The alpine rhododendron is an evergreen shrub or small tree of the family Ericaceae, with a plant height of 1-3 m, stout branches, and leaves clustered at the top of the branches, thickly leathery, 6-12 cm long and 2-5 cm wide. It blooms in April-May, mainly with double-layered and double flowers, and also a small number of single flowers, with a flowering period of about 1 month. Flower colors include white, pink, light red, peach red and yellow. It generally grows in the wild at an altitude of 600-800 m, has strong adaptability, and after artificial domestication and cultivation it is expected to become an evergreen ornamental plant in gardens and green spaces.