The complete guide to Osmanthus: a full overview in one article

Osmanthus is the collective name for many trees in the genus Osmanthus of the family Oleaceae, also known as rock osmanthus, Jiulixiang, and Jinsu. It is one of China's traditional top ten flowers, an excellent landscape tree that combines greening, beautification, and fragrance, with both ornamental and practical value. It is widely used in landscape construction, and there are many horticultural varieties, the most representative being Jinguì, Yingui, Dangui, and Yuegui. In ancient Chinese poetry praising flowers, the number of works praising osmanthus is also quite considerable, and it has been deeply loved by Chinese people since ancient times.

Osmanthus is an evergreen tree or shrub, 3 to 5 m tall, and can reach up to 18 m at its tallest, with grayish-brown bark and yellowish-brown branchlets. The leaves are leathery, elliptical, oblong-elliptical, or elliptic-lanceolate, with the base gradually narrowed into a wedge shape or broadly wedge-shaped, entire or usually with fine serrations on the upper half, hairless on both sides, and the glandular dots on both sides forming small blister-like protrusions. The cymose inflorescences are clustered in the leaf axils, or nearly broom-like, with multiple flowers in each axil, the bracts broadly ovate, the flowers extremely fragrant, and the corolla yellow-white, pale yellow, yellow, or orange-red. The fruit is skewed, elliptical, and purple-black. The flowering period is from September to early October, and the fruiting period is March of the following year.

Osmanthus is adapted to subtropical climate regions and prefers warmth and humidity. The average temperature in cultivation areas is 14 to 28°C, the average temperature in July is 24 to 28°C, the average temperature in January is above 0°C, it can withstand a minimum temperature of -13°C, and the most suitable growth temperature is 15 to 28°C. Humidity is extremely important for the growth and development of osmanthus, requiring an average annual humidity of 75 to 85% and annual precipitation of about 1000 mm. Especially in the young stage and when mature trees bloom, more water is needed. If drought is encountered, flowering will be affected. Strong sunlight and shade are unfavorable to its growth, and generally 6 to 8 hours of light per day are required.

Osmanthus is native to the eastern section of the Himalayas in southwestern China, and is also distributed in India, Nepal, and Cambodia. Wild osmanthus grows in southwestern China, Sichuan, southern Shaanxi, Yunnan, Guangxi, Guangdong, Hunan, Hubei, Jiangxi, Anhui, Henan, and other places. It is now widely planted in the Huaihe River basin and areas to the south. Its suitable growing area can reach as far north as the lower reaches of the Yellow River and as far south as Guangdong, Guangxi, Hainan, and other places, and has formed several nationally famous osmanthus commercial production bases in Lu'an, Anhui; Xianning, Hubei; Taoyuan, Hunan; Suzhou, Jiangsu; Guilin, Guangxi; Wuhan, Hubei; Hangzhou, Zhejiang; and Chengdu, Sichuan.

After long-term cultivation, natural hybridization, and artificial selection, osmanthus has produced many cultivated varieties. Through further investigation and sorting, 32 osmanthus varieties have been preliminarily identified. By flower color, there are Jinguì, Yingui, and Dangui. By leaf type, there are Liuyegui, Jinshangui, Dishuihuang, Kuihuaye, and Chaibinghuang. By flowering period, there are Bayuegui, Sijigui, and Yueyuejia, among others.

Osmanthus is pale yellow-white and fragrant. Aromatic oil is extracted from it, and osmanthus concrete is made, which can be used in food and cosmetics, can be made into cakes and candies, and can also be used to brew wine. Osmanthus is pungent in taste and can be used as medicine. The flowers, fruit, and roots are used medicinally. Flowers are collected in autumn, fruit in spring, and roots in all four seasons, and each is sun-dried separately. The flowers are pungent in taste and warm in nature, with the effects of dispersing cold and breaking stagnation, and resolving phlegm and relieving cough, and are used for toothache, cough and asthma with excessive phlegm, and amenorrhea with abdominal pain. The fruit is pungent and sweet in taste and warm in nature, with the effects of warming the stomach, calming the liver, and dispersing cold, and is used for deficiency-cold stomach pain. The root is sweet and slightly astringent in taste and neutral in nature, with the effects of dispelling wind-dampness and dispersing cold, and is used for rheumatic muscle and bone pain, low back pain, and kidney-deficiency toothache.