What to know about Rehmannia glutinosa (chinese foxglove) before using it medicinally

Rehmannia glutinosa, commonly known as Chinese foxglove, is a medicinal herb that has been extensively used to improve various health conditions, including fever, hypertension, and anemia, by modulating the body's energy and promoting vitality.

From a horticultural standpoint, Rehmannia glutinosa is a perennial plant that thrives in damp environments and requires careful cultivation to prevent over-maturation. From a botanical perspective, Rehmannia glutinosa is classified as a member of the Scrophulariaceae family, characterized by its unique tuberous root system and showy, foxglove-like flowers.

Historically, Rehmannia glutinosa has been used in Traditional Chinese Medicine for over 2,000 years, with recorded mentions in the Shennong Bencaojing, one of the earliest Chinese medical texts.

This article explains the medicinal, horticultural, botanical, and historical aspects of Rehmannia glutinosa.

What are the medicinal properties of Rehmannia glutinosa?

Rehmannia glutinosa helps with cardiovascular problems, anemia, and menstrual disorders. It is also used to treat bronchitis, rheumatism, and arthritis. Additionally, it is used as a tonic to boost energy and vitality.

The medicinal properties of Rehmannia glutinosa are attributed to its active constituents, including starch, glucose, and flavonoids such as kaempferol and quercetin. These compounds have antioxidant, anti-inflammatory, and vasodilatory effects, contributing to the plant's medicinal benefits.

The root of Rehmannia glutinosa is the most commonly used part for medicinal purposes. It is typically harvested in the fall and used fresh or dried. The root contains the highest concentration of active constituents, including the starch and flavonoids responsible for its medicinal effects.

When used improperly, Rehmannia glutinosa can cause gastrointestinal upset, dizziness, and allergic reactions. Consume excessive amounts can lead to over-stimulation of the cardiovascular system, increasing blood pressure and heart rate.

To use Rehmannia glutinosa medicinally, precautions should be taken, such as consulting with a healthcare professional before consumption, especially for individuals with pre-existing medical conditions, taking medications, or pregnant/breastfeeding women.

What are the horticulural aspects of Rehmannia glutinosa?

Rehmannia glutinosa, also known as Chinese Foxglove, grow best in partial shade to full sun with well-draining soil rich in organic matter. It requires a slightly acidic to neutral soil pH and high humidity. Temperature tolerance ranges from 35°F to 75°F (2°C to 24°C).

For optimal growth, plant Rehmannia glutinosa in the fall or early spring, when the weather is mild. Avoid transplanting during hot weather, as it can lead to root damage. Plant tubers 2-3 inches deep and 6-8 inches apart, with the eye facing upwards.

Harvest Rehmannia glutinosa tubers in the fall, about 10-12 months after planting. Dig carefully to avoid damaging the tubers, and lift them before the first frost. Allow the tubers to dry in a warm, dry place for 2-3 weeks to prevent rot.

Rehmannia glutinosa is susceptible to root rot, caused by excessive moisture and poor drainage. Other common issues include fungal infections, such as rust and leaf spot, and insect pests like aphids and spider mites. Regularly inspect the plant for signs of disease or infestation.

What are the botanical aspects of Rehmannia glutinosa?

Rehmannia glutinosa is a perennial herb with a thick, fleshy, and taprooted stem that can reach up to 30 cm in height. The leaves are ovate to lanceolate, 10-20 cm long, and 3-5 cm wide, with a waxy texture and a glaucous sheen.

The taxonomical classification of Rehmannia glutinosa places it in the family Orobanchaceae, order Lamiales, and clade Asterids. It is closely related to the genera Orobanchus and Lathraea, and its closest living relatives are the broomrapes and the Indian pipe cactus.

Rehmannia glutinosa has several variants, including Rehmannia glutinosa var. glutinosa and Rehmannia glutinosa var. purpurea. The former is the more widely distributed of the two and is found in most parts of its range. The latter is found only in the southern parts of China.

Rehmannia glutinosa is native to China, where it is widely distributed in the provinces of Jiangsu, Jiangxi, Fujian, Zhejiang, and Yunnan. It has also been introduced to Taiwan, Korea, and Japan. In its native range, it grows in wetlands and along streams at elevations of up to 1,500 meters.

The life cycle of Rehmannia glutinosa begins in the spring when the plant emerges from dormancy and produces new leaves and stems. In the summer, it produces purple flowers that are clustered in a raceme. The flowers are followed by seed capsules that contain many small seeds. The plant then dies back in the fall, but its roots remain viable until the following spring.

What are the historical aspects of Rehmannia glutinosa?

Rehmannia glutinosa, also known as Chinese Foxglove, is a medicinal plant with a long history of use in traditional Chinese medicine, dating back to the Han Dynasty (206 BCE - 220 CE). Its roots and rhizomes were used to treat a variety of ailments, including fever, diarrhea, and insomnia. It was also used as a tonic to promote longevity.

In Chinese mythology, Rehmannia glutinosa is associated with the mythical figure of the Eight Immortals, who are said to have used the plant to prolong their lives. According to legend, the plant's roots and rhizomes were considered to have magical properties that could bring eternal youth. This mythological reference solidified the plant's importance in Chinese culture.

In Chinese culture, Rehmannia glutinosa is also associated with the concept of yin-yang and the five elements. The plant's properties are seen as having yin characteristics, while its roots and rhizomes are associated with the earth element. This symbolic meaning is still used in traditional Chinese medicine today.

Historical texts such as the Shen Nong Ben Cao Jing (Divine Farmer's Herb-Root Classic) and the Ben Cao Gang Mu (Compendium of Materia Medica) describe the use of Rehmannia glutinosa in traditional Chinese medicine. The Shen Nong Ben Cao Jing, written in the 2nd century CE, lists the plant's roots and rhizomes as a treatment for fever and diarrhea.

Archaeological artifacts from the Han Dynasty have been found to contain Rehmannia glutinosa roots and rhizomes, demonstrating the plant's use in traditional Chinese medicine during this period. The discovery of ceramic jars containing the plant's roots and rhizomes has provided evidence of the plant's historical importance in Chinese culture.